GIAC AN HINH 12 CB ( DA SUA)

Trường THPT Long Hữu Giáo án Hình học 12 cơ bản    !"#$% &'() 1. Về kiến thức   !"#"" 2. Về kĩ năng $%&" 3. Về tư duy và thái độ '()*"+,-.//-01".2!34 ')*+ 1. Chuẩn bị của giáo viên: 5.+6"&7( $8"/ 2. Chuẩn bị của học sinh 9".:&)!4; <3=>?"2@"!/AB).  !"CD";4EE ,-./,$ 0 ,FG" H "."I J I H K L  L   1234(45, 6789<!:2: :;<=>?@M7F?"2@"!/AN  > '!O)8"/APA9Q$0RS@"!/Q$0RSQT$T0TRTSTU EV95<WX*A@"!/FY 9ABC<DEF9A?9GH 7I? J =/ 7I?K=L IM Z0[!\A9Q$0R "I L &]"C ZA#""^ __!"_"5` X*A _#"""4&); A8AAU@" !/.A/aI"-W ZbF!"-A&" AN Za:M7!)7 'F1@"!/.A c[.&.C)F.C7.& )F.&71A. @"!/ Za:" C"4&1 A"FM F Z<-;Q0% A&"]"  L 3"> Z(:8%  "FM C! N# Khối lăng trụ (khối chóp) là phần không gian được giới hạn bởi một hình lăng trụ (hình chóp) kể cả hình lăng trụ (hình chóp) ấy. Z<A/UI"-W Z5F"d>điểm trong điểm ngoài1A.A / Za:)F L  !" "1@"!/.  L  Zc!"." 1A.# L @" !/U95<W E Trầm Tấn Phong Trường THPT Long Hữu Giáo án Hình học 12 cơ bản 9OP;EQ9R97=MPEF9A7=MP #/ #L S%)/ T<U>H9DVWXFY<F C1A9Q$0RS a!/Q$0RSQT$T0TRTSTN Z5F%e." ZA@"!/!F A]""N Zb%e">:"1 C":QSS f Q f  $00 f $ f BQ$$ f Q f $00 f $ f B9Q$ 90RN Tgh&1AC1 @"!/!F&"1i7 " Z',]"%e!FM7F aN Z'I"-A@" !/M7)>  Z0(:"F395< * !".".>!".> "1 Z0"([.&.C. !"."1 """(1@" !/A Z54%&"]" ".]" #"8]" U`R95<j!kW Z'8%cl:"!"m Z'8%- &"!F Z(:8% !F>A "]"#" "&);:  G &" Z'8%% e#"A"B AE&"BAE " Z<%&" 1" Za:)  Z'!8 < _#"""4 &);. 8A + H/s thảo luận vì sao các hình trong ví dụ là những khối đa diện. + Thảo luận HĐ3(sgk) 0A&&" 1)"F#" 83F%7 #"8  9OP;EQ9R97= MP U95<W  9OP;EQF9A7=  MP VFY N %L/ W'K?AZM[M\ b*&a.N !FK7#"N `>)E.^aE^.():&_n& W] ^ Trầm Tấn Phong / W $ ' %    /  /  /    Trường THPT Long Hữu Giáo án Hình học 12 cơ bản  !"#$%VY &'() 1. Về kiến thức   !"#"" 2. Về kĩ năng $%&" 3. Về tư duy và thái độ '()*"+,-.//-01".2!34 ')*+ 1. Chuẩn bị của giáo viên: 5.+6"&7( $8"/ 2. Chuẩn bị của học sinh 9".:&)!4; <3=>?"2@"!/AB). !" CD";4EE ,-./,$ 0 ,FG" H "."I J I H K L  L  1234(45, 6789<!:2: :;<=>?@  > $#$%^/$) 7I? J =/ 7I?K=L I% Zo)  !"#"" a-!"bFaN Z'81&D"Q$ Y v T  Z'81&D"Q$ Yc   Z'81&D" Q$Yc  Z'^QT.$T: CD"UoWCD" !"!-1&QQTB$$T Zb*&a v T Bc  Bc   ZbF>ác phép dời hình trong không gian? Z95< ZpF)8"P cA _899U v _,9`H7Aabc=;[ H9dV,Y _,9`H7Aabe;f _,9`H7Aabc=;[ 7gh9dM ,9`HMh9R9< F9i= N#'!"#"". Y7*CI"3"h g4g f e ?7i" )!"#"" qo)!"#" "" A )88""] rd q %0  !"#""UsO: "W Z'I"-  !"CD"A%e "> !" #""N Zo)%e * Nhận xét: W'-F  :P   )Wo )  f .) [.&.C1 [.&.CI"3" 1 f l Trầm Tấn Phong Trường THPT Long Hữu Giáo án Hình học 12 cơ bản Z'I"-!"C D".M7a^)t" !"#""N Z'!O)8"/UEE^aEu 95<WM7aUWvU ff WN ZpcVN U5F"do  )@"!/ Q$RQT$TRT@"!/ $0R$T0TRT b%e">w" 1 "W Z"()t" A  )7  ZoOOI v r ) UWU f W.eK w)U f WU ff W`%7 UWvU ffW Z5(w"  "QT0.Q0Tw x!"1 &QT0.Q0T.$TR.$RT RAAe3" Kw)@"!/ Q$RQT$TRT@"!/ $0R$T0TRT ⇒  =9R9>j9= N#899k=VFY ZcC) "()t"A  ) 7 q`R95<aEu /= J  5(w"  "QT0.Q0Tw x!"1 & QT0.Q0T.$TR.$RT b%7A e3"Kw)@" !/Q$RQT$TRT@" !/$0R$T0TRT ⇒    ,9e?9=EBlH9`H?O?F9A7=MP fm#S/'n$/ fm#o p /'n$L S%)/ Z'!O)/UEEl95< !"EEWM7)> K7*" &4 0a:Y:lUW. U E WBU ^ W ZUW1U E WU ^ W ZU E WU ^ W#"A "!" qbUW 1 E  ^  : E  ^   #"A "!".AA   E  ^ 7A*"  E  ^ 4 UW ZR6"CD" %I" Q$0RQT$T0TRT: 3 Z5d 0%I" @"!/" 0h@"!/ "l3 Z5F%e ZoKx[!\I)t" x/95< Z:-O"d 1"F Z:!)71  q`R95<aEE Z9qa`g )ir#AK ]"3 V Trầm Tấn Phong O D' C' B' A' D C B A Trường THPT Long Hữu Giáo án Hình học 12 cơ bản W'K?AZM[M\ _qH0A3">9Q$0R api7^g.b4g>!"1Ab>"1A )aoKA!F)A:VAA)t" `>O().)%EB^BlBV!"E^!"95< qqqqqqqqqqqqqqqqqquuuuuqqqqqqqqqqqqqqqqqqqqqqq ]  r,"#$% D?s  QF9b? 01">.)t"  QFtC $%&".#"8 `%/" !"#""K.3" )t" $KI"8  QgMZ9O7I yz7(:{@"Kx.|""8) (:(%x- '9u>8?K=OEsE9v?9 5`5.)8"/ 9()!4)% E V→ !"E^95< ,9gwH9OH5;.i  <R9M9v? 6789<:2: :;<=>?@ 5`!O)8"/UP%I"W M7%I":@"!/)t"N ;x  #U$'E!"E^95<W “Cm rằng một đa diện có các mặt là những tam giác thì tổng số các mặt của nó là một số chẵn. Cho ví dụ”. 7I?K=/ 7I?K=L /9>y 4"X9"8 Z58:}AC 'a:~ Z0A%e">:& 17N Zb%e[:} 0x/N 'O\ gh&1UW& "1CF: &1UWv l ^ m  3AVC L/ 58:}UWAC RhCAl&F CAl& gh&1UW&" 1CF:&1UW v l ^ m R"7FI" F8:~UW `R3AVC • Trầm Tấn Phong  D' C' C B A' B' A D Trường THPT Long Hữu Giáo án Hình học 12 cơ bản  # U$'l!"E^95<W“Chia khối lập phương thành 5 khối tứ diện”. 7I?K=/ 7I?K=L /9>y '!O)8"/A3 %I" €F_9F"8  5(9%e 5`%e.[:}  pF)8" L/ '@"!/•3 QQf$R.$fQf$0f.0$0fR. Rf0fRQfRQf$0f #58$'VaE^95<“Chia khối lập phương thành 6 khối tứ diện bằng nhau”. 7I?K=/ 7I?K=L /9>y 5`!O)8"/A3 %I";K• <'$0 5;9 Z'[_% I"‚3 )t" Z'OK•<'$0. OM%I" @"!/)t"  Zc‚3 )t"_ N 5(9!8  5(9%e b%e.[: G   D' C' C B A' B' A D 'O\ o![_ h@"!/) 3)t" 97"2 @"!/Q$RQf$fRf l3)t" b%e!8 1)& WL/ '@"!/Q$RQf$fRf l3$Qf$fRf. QQf$RfQR$Rf oe3"YUQf$RfW )3$Qf$fRf3 QQf$Rfe3" YUQ$RfW)3 QQf$Rf3QR$Rf F)3!F)t" pI"-4@"!/ $0R$f0fRf %I"‚3)t"  W'K?AZM[M\ U5`!O)8"/$'laE^95<W Hãy chứng minh hai tứ diện AA’BD và CC’BD bằng nhau? 58$'n& 9&!4)ƒ<+>„ qqqqqqqqqqqqqqqqqqqquuuuuqqqqqqqqqqqqqqqqqqqqqqq ‚ Trầm Tấn Phong Trường THPT Long Hữu Giáo án Hình học 12 cơ bản ] WW "#$%4z "#$%#!) _D?s  QF9b? p(:*+.>  QkĩC b%)&.:)FY yz7{@"P#""  QgZ9O7I '7!-Y#"Y%A&"$Y:- _0Ax-!"(%xF- _'9u>8 'K=/ 5.4.)8"/ 'K=L<3>.:&)!4; _,9gwH9OH'!-Y.";.i  _<R9BsBxH 6789kA :;<=>?@  > 9A7=MPB{ 7I/ 7IL IM Z'!O)8"/UE.EkaEVW. (:(."F3_ >+ ZbFN Z'!O)8"/UEEmaE•95<W ZsOP.%e. ) Z<@"!/". .3 ]"+ N#F9A7=MPB{ VL/Y q`RU95<aE•W qb" aE + [>!"1A #t>Exah 3EC1A 9A7=MP7Q k Trầm Tấn Phong Trường THPT Long Hữu Giáo án Hình học 12 cơ bản W' J ?AZM[M\ Zb*&+.> Z$%0aKC1E%I"[1E)> Zp … )E.^.l.VaEm95< qqqqqqqqqqqqqqquuuuuuqqqqqqqqqqqqqqqqqqqqqqqq  m Trầm Tấn Phong 7I/ 7IL IM Z0(:eO:# > L # L  L F J F … .# L K J  I"5 J :K J eO L F … @ J  …  † H  H  L # L  L N ZcaF … # L F J F …  Z'!O)/UE^uaE‚95<W."( (:%e," &N Zo) J 7 L N Z'!O)8"/U$8"''*1• &>W Z‡:PF>_a Z0(:" )FN + ‡: L #† …  L  F J F …  … # L K J  I".!K J eO L  F … @ J .† H  H  L # L   L  Zo L )F H a Z:!8  Z95< Z0aˆ‰SŠgb )> Z0a"m "ˆSŠ.ˆŠg.ˆgb. ˆbS.‰SŠ.‰Šg. ‰gb.‰bS]" ">&a^ N#VL/Y N#4VL/Y N %:“Chứng minh rằng trung điểm các cạnh của một tứ diện đều cạnh a là các đỉnh của một bát diện đều.” /= J  '9bMP7Q$'%Z ?9=/vZ|Z}Z~ZE BBg•B<7:;?O? ?9$'Z%Z$Z''%Z E%$ =?G=;O?]=;O? }~Z~ZZ}Z|}~Z |~Z|Z|}B9€ =;O?7Q?9= qZ|Z}Z~ZZB?O? 7•9?K=>OMP7Q N E M F I A D B C J Trường THPT Long Hữu Giáo án Hình học 12 cơ bản Ngày soạn:28/8/2010 Tuần 5. Tiết 5 r,"#$%4z "#$%#!) _D?s  QF9b? - <*:K&?"2xi8+.> - b%)&+.>  QFtC - yz7{@"3">"8)%>+ > - yz7{@"P#""  QgME9O7I yz77!-Y - b%)&+> - 'x-&" _'9u>8?K=/ EL - 5`'4.)8"/ - 9b*]"d70‹)?)%;'4Œ• _,9gwH9OHyM";.i  _<R9BsBxH E 6789BxH ^ :;<=>?@ Eao)?"2+.>xi1Ž"N ^abF&>N0x/>>!"-N l > 7I58)%^:"!"Em &"15` &"19 bR" Z'!O)8"/E^^ :"!"Ek Z€F_9e? UWUfW Z• 0C1UW "N 0C1UfW "N bFxx1 C1UW UfWN bFx_ 1UWUfWN Z5`[:9 !)7e" ZbP!F )8"/e? UWUfW Z#" Z'"> R#" ^ R">& ^ ^ a  ^ E ^ l ^ ^ ^ a   × ×  ÷  ÷   NqH:"!"Em 58 cC1%I" UW.A&1) >UfW)*" ^ ^a Rx_1UW )t"‚ ^ Rx_1UfW )t" l m l m ^ ^ a a = `%7[:x_1 UWUfW l^ l ‚ ^ ^ = a a • Trầm Tấn Phong Trường THPT Long Hữu Giáo án Hình học 12 cơ bản 7I]L/ 7I?K=/ 7I?K=L I% Z5`!O)8"/P !F)8" Z• 3>& ,K1C 13F>Q$0R N bF3" 5 E 5 ^ 5 l 5 V 3 >N Z'x&5 E 5 l N Z5`xe&Y8 Z9P p35 E 5 ^ 5 l 5 V  0a37A‚& >)t" Z9%e Z'A ll E l ^ l ^ lE l E lE a BDMNGG AN AG AM AG MN GG ===⇒ === qH:"!"Em 03"!t"K1 C13>[ 13> 58 s3>Q$0RA &)t"5(g.b.<_ !"1&$0.0R. QR5(5 E .5 ^. 5 l. 5 V _ !("K1CQ$0.$0R. Q0R.Q$R 'A ll E l ^ l ^ lE l E lE a BDMNGG AN AG AM AG MN GG ===⇒ ===  03"I"-A &5 E 5 ^ v5 ^ 5 l v  5 l 5 V v5 V 5 E v 5 E 5 l v l a :7!3 5 E 5 ^ 5 l 5 V 3> c>A3"•K1C 13>Q$0R [13> 7I58)%V:"!"Em &"15` &"19 bR" Z'!O)8"/P!F )8" a5`"d '3"Q$ŠR"N '3"Q$ŠR QŠ$RAxi "N Z0&D"QŠ. $R.0S*!" 1h " Z9P; Z ZQŠ⊥$R Z'3"Q$ŠR FQŠ$R* &!"ˆ 1h " NqHW:"!"Em 58 a03"!t"QŠ.$R0S# #""A4*& !"1h " R$.0.R.S>QŠ FŽ"6"CD"!" !-1&D"QŠ'I"-Q.$. Š.R6"D"Q.0.Š. S="6"CD" Eu Trầm Tấn Phong / W $ ' %   /  /  /    % $  ' ~ }  [...]... Tip im ca (S) (P): Mp tx hay tip din ca (S) (Hỡnh 2.19/44) * Chu y: (P) tip xỳc vi S(O; r) ti H (P) OH ta i H 3/ TH3: h < r 3) Trng hp h < r: (P) c t (S) theo ng tron (P) (S) = (C) (C) Vi (C) l ng trũn cú tõm H, bỏn kớnh r = r 2 h 2 + Nu gi M = (P)(S) (Hỡnh 2.20/44) Xột OMH ta cú: MH = r = r 2 h 2 * B: khi h = 0 thi H O Do o C( H ; r ) Khi o ng tron giao tuyờ n + (P) (S) = C(O;r) C(O; r) gl... (S) v (P) ? Giỏo ỏn Hỡnh hc 12 c bn H HS + d(O; P) = OH NễI DUNG * Cho S(O ; r) v mp (P) Gi H la hỡnh chiu ca O lờn (P) Khi ú h = OH la k/c t O ờ n (P) Ta co 3 trng h p sau: + Co 3 kha nng xay ra: 1/ TH1: h > r Trờn (P), ly 1 iờ m M bt 1) Trng hp h > r: k ta co: OM OH > r (P) (S) = =>OM > r (Hỡnh 2.18/43) => M (P), M (S) => (P) khụng c t (S) 2) Trng hp h = r : (P) (S) = {H} + (P) tip xỳc vi (S)... ln ca mt cu (S) (Hỡnh 2.21/44) Mp i qua tõm O gla mp kinh cua m/c 2/ TH2: h = r Trờn (P), ly 1 iờ m M bt k, M khac H, ta co: OM > OH = r =>OM > r Khi o H la iờ m chung cua (S) va (P) Ta noi (P) tx vi (S) ta i H + Tim tõm va bk cua (C)? (GV gi ý) + Khi h = 0 thi (P) (S) = ? + Khi o C(O; r) gl ng trũn ln ca mt cu (S) (Hỡnh 2.21/44) Mp i qua tõm O gla mp kinh cua m/c + () (S) = ? + Gi H l hinh chiu ca... khi a din c t tng ng vi mt s dng duy nht V (H) tho món 3 tớnh cht (SGK) + Giỏo viờn dựng bng ph v cỏc khi (hỡnh 1.25) - Cho hc sinh nhn xột mi liờn quan gia cỏc hỡnh (H0), (H1), (H2), (H3) Tớnh th tớch cỏc khi trờn? + Hc sinh ghi nh cỏc tớnh cht +V(H1)=5V(H0)=5 V(H2)=4V(H1)=4*5 V(H)=3V(H2)=3*4*5 Ni Dung I Khỏi nim v th tớch khi a din 1.Khỏi nim SGK) 2 nh lớ(SGK) + V= abc - Tng quỏt hoỏ a ra cụng thc... ng thng v m/c (S) trong khụng gian + Cho S(O; r) v H la hỡnh chiu ca O lờn => d(O; ) = ? + khụng c t (S) khi nao? + tiờ p xuc (S) khi nao? + T ú, nờu tờn gi ca v H ? H HS + HS nhc li kin thc c + khụng c t (S) + tiờ p xuc (S) + c t (S) + d(O; ) = OH = d NễI DUNG * Cho S(O; r) v ng thng Gi H la hinh chiu ca O lờn => d(O; ) = OH = d Ta co 3 trng h p sau: 1) d > r : => (S) = (Hỡnh 2.22/46)... => (S) = + d = r => (S) = {H} + H go i la tip im ca v(S) : Tip tuyn ca (S) + d < r =>(S) = {M, N} 2) d = r: => (S) = {H} Ta noi: tip xỳc vi (S) ti H H go i la tip im ca v (S) : Tip tuyn ca (S) + c t (S) khi nao? * tip xỳc vi S(O; r) ti im H OH = H + c bit khi d = 0 thỡ + d = 0 thi qua O va c t (Hỡnh 2.23/46) sao? (S) ta i A, B + on thng AB khi ú + Ta co AB l ng kớnh 3) d < r: => (S)... AI.BI.SO (1 ) 3 3 2 1 a 3 a a 11 a 3 11 = = ( vtt) (0 ,5 ) 6 2 2 24 3 S 2: Cõu 1 1 SABCD.SA (0 ,5 ) 3 1 8 = 2a.2a.2a = a3 (1 ) 3 3 b) K IO (ABCD) IO//SA (0 ,75 ) a) Ta cú: VS.ABCD = a I A B M I l trung im SC nờn O l O SA 2a = =a (0 ,75 ) 2 2 D 1 1 4a 3 Vy IABCD = IO.SABCD = a (2 a)2 = (vtt) ( 0,5 ) 3 3 3 trung im AC IO = Cõu 2 : a) Vỡ IBC cõn ti I v IMl trung im BC nờn BC IM ( 0,5 ) ABC u BC AM (0 ,5... +Khi hp c chia thnh khi t din ACBD v 4 khi chop A.ABD, C.CBD,B.ACB, D.ACD +Cú cựng dt ỏy v chiu cao +V = VDADC + VBABC +VAABD+ VCBCD + V1 M VDADC = VBABC = VAABD 1 S 1 h= V 6 = VCBCD= 3 2 4 1 V =V V = V 1 6 3 V V y : V = 3 1 B C A B Gi V1 = VACBD V l th tớch khi hp S l din tớch ABCD h l chiu cao V = VDADC + VBABC +VAABD+ VCBCD + V1 M VDADC = VBABC = VAABD 1 S 1 h= V 6 = VCBCD= 3 2 4 1 V1 = V V = V... (0 ,5 ) BC (AIM ) BC IA ( 0,5 ) IO (ABC) ( 0,5 ) b) Gi O l tõm ỏy ABC 2 3 2 b 3 b 3 = 3 2 3 Ta cú : AO = AM = C 0,5 I 2b ( 1) Xột IOA vuụng ti O A C 2 IO = IA2 AO 2 = ( 2b ) 2 b 3 b 11 (1 ) 3 ữ = 3 ữ Vy th tớch khi chúp S.ABI l : b 0.5 O M B 1 1 1 AM.BM.IO (1 ) 3 3 2 1 b 3 b b 11 b3 11 = = ( vtt) (0 ,5 ) 6 2 2 24 3 V= SABM.IO = 24 Trm Tn Phong Trng THPT Long Hu Giỏo ỏn Hỡnh hc 12 c bn Ngy... tuyn ca mt cu S(O; r) v O trờn () mp () , bit d(O ;() ) = r/2 r Ta co: OH = h = 2 => () (S) = C(H; r) r 2 r 3 = 4 2 Vi r = r2 Vy C(H; r 3 ) 2 4 Cung cụ , d n do: - Nh c la i /n m/c, khụ i cõ u va giao cua m/c vi mp? 35 Trm Tn Phong Trng THPT Long Hu Giỏo ỏn Hỡnh hc 12 c bn - Hs vờ ho c bai, soa n phõ n con la i va lam bt 1, 2, 5, 7/49 SGK *************************************** Ngy soa n 12/ 11/10 Tuõ . 3"> Z ( :8%  "FM C! N# Khối lăng trụ (khối chóp) là phần không gian được giới. QgMZ9O7I yz7 ( :{@"Kx.|""8)  ( : ( %x- '9u>8?K=OEsE9v?9