KHAI THAC BAI TAP HINH HOC LffP 8 NHAM BOI OITONG TUDUY SANG TAO CHO HOC SINH TRUNG HOC COSO ThS HOANG TH! THANH" I Mgtsovaidechungvehrduy sang tao (TDST) Trong hgc tgp mdn Toan, TOST la mdt dang tu d[.]
KHAI THAC BAI TAP HINH HOC LffP NHAM BOI OITONG TUDUY SANG TAO CHO HOC SINH TRUNG HOC COSO ThS H O A N G TH! THANH" I.Mgtsovaidechungvehrduy sang tao (TDST) Trong hgc tgp mdn Toan, TOST la mdt dang tu dgc lap nhSm tao y tudng mdi dgc dao, cd hieu qua giai quyet van de cao; dd la kha nang phat hien vain de, tim hudng di mdi va lao kel qua mdi vdi cac giai phap la, hiem khdng quen thugc hole nhat Nhieu nghien cuu da dua eac eau true khac cua TOST, luy nhien cd the hieu TDST eua HS dugc dac trung bdi ba yeu td eo ban sau: + Tinh mem deo (ffexibility): La kha nang d l dang chuyen ll)hogl dgng tri tue sang boat ddng tri tue khac; + Tinh nhudn nhuyen (fluency): La kha nang lim dugc cac giai phap dudi nhieu gdc va linh hud'ng khac nhau; + Tinh dpc dao {originality):la kha nang tim va quyet djnh phuang thuc giai quyet la hoac nhat Cac yeu tddac trung coban cua TDST khdng lach rdi ma trai lai, chung cd mdi quan he mat Ihiet, hdtrg bd'sung cho va ed mdi quan he khang khit vdi eac yeu td khac nhu: tinh chinh xac, tinh hoan Ihien, tinh nhay cam van de, Tat ca cacyd'u tddactarng cung gdp phan tao nen TDST, d?nh eao nhat eae hoat dgng tri tue cua ngudi Cd thevan dung eac hoalddng tri tue de giai cac baitoan(BT)dachovadudoanketqua,timra phuong hudng giai; tudd, md rgng, dao sau va he thd'ng hda cac kie'n thde, phat hien van demdihoae nhin thay sulien he giua nhieu van de vdi Nhd dd, HS cd the giai quyet nhung van de tong quat hon, van de tuong tu, hoae di sau vao eac truang hop dae biet 1) Khai thac, de xua't BT mdi td mpt BT da cho Tucach giai cua BT da eho, ta se lim cac didu kien eo ban, yeu td khong ban ehdt de ed the suy cac BT tuong tu, BT din xua't Qua dd, giup HS ren luyen cac hoat ddng tri tue nhu: phan tieh, long hop, so sanh, tuong tu, truu tugng hda, dae biet hda, khai qual hda, he Ihdng hda Tu do, phal hien nhutig van de mdi, BT mdi va Idi giai tuang ung Day ia mdt giaiphap huu hieu de bdi dudng TDST eho HS BT/.'Cho lam giae ABC vudng tai A.Chgn A Iam dinh, theo thu tu dung phia ngoai tam giac ABC cac tam giac vudng can CAE va BAD Ggi P,0, Mian luollatning diem eua BD,CE,CB(/)/W/7/) ^ a) So sanh BE va CD Xac dinh gdc giua haidoan thang dd b) Chung minh PMQ la tam giac vudng can Hudngdan: a) Tu gia Ihiet d l dang suy/a cae diem B,A,Elh§nghang;C, A, D thSng hang Suy r a B E l C D vaBE = BA+AE=DA+AC= CD Ngoai ra, ehung ta can quan lam ldi mdt vai yeu td d|c trung khac ciia TDST nhu: + Tinh hoan thien (elaboration): La kha nang lap ke hoach, phd'i hgp giOaynghlvahanh dgng, phatlrien ytudng kiem tra va chung minh y ludng; + Tinh nhay cam van de (probhm'ssensibiiity):Lanang lue nhanh ehdng phat hien ravande,sumauthuan,saitam,sulhieu logic, ; bjTi) giai thiel suy dodd y mudn ca'u InJe lai hgp li, hai hda, tao ra MP la dudng tmng c^mdi binhcuaABDC,dodd, B M c 2.Khaithacbaitap hinh hoc lopSdeboldudng MP//CDvaMP = 1/2CD(1) TDST ChoHS Tuong tu, MQ la dudng tmng binh cua ABEC nen -VilcbdidUdngTDSTchoHS can dugc tien hanh MQ/yBEvaMQ = 1/2BE(2).Tu(1)va(2),kethgpvdi trgng ma quan hd huu co vd^ cac hoat dgng tri tue ketquaeaua)suyraMP = MQ v a M P l M Q h a y Nhac nhu: phan lich, tdng hgp, so sanh, tuong tu, truu A M P Q vudng can tai M tugng hda, die biet hda, khai quat hda, he thd'ng hda; ,.|||g do, phan tich va td'ng hgp ddng vaitrd nen tang * Khoa toan - Li - Tin, TnriUng Dai hoc Tay 8^c Tap chi Gido due so 314 (ki2r 7/2013)- 49 Nhanxet /.'Giasu'tam giac ABC cho trudc khong , cdthi'dugc phatbieu theo nhi^u each khac ^hai la tam giac vudng ma )a tam giae thudng, cd Mgtcachkhac'dephatbid'uBT: •^flrff.'Dungra phia ngoaitam giac ABC cho tnrdc A< 90° ching han Thiet lap BT tuong tu, nhtJng dieu da chung minh dugc d tren cd cdn dung khdng? cachinhvudngBADGvaCAEF.GgiP.Qtheothiiti Ta thay, vdi A< 90° thi eae diem 8, A, E khdng thing ia lam cac hinh vudng BADG va CAEF, M la tnJj" hang va C, A, D khdng thing hang; d l dang chung diem eiJa BC (hinh2) Chung minh rling: a) BE = minhdugcADAC = ABAE.Dodd,BE = CDvaACD = va BE CD; b) A E B Gpi I la giao diem cua BE va CD, d l dang suy Tam giac PMQ vudng can, el5 = 90^ Tuong lu, ta cung thu dugc kdt qua nhu cSu b) NhSn xet 6: Id cua BT Nhu vay, vdi gia thiet A< 90", ta cd BT luang hinh ve cua BT6lai tuBT duge phat bieu nhusau: ggi y cho HS mgt each khac dd' khai fi7'2.'CholamgiacABC(cdA 90") Chgn A lam ban dau Mdt cac phuong phap thudng sudwr^ dinh, theo thir tu dung phia ngoai lam giae ABC de tim kiem loi giai ciJa mdt BT la thay da each ph^ b i l l cac tam giae vudng can CAE va BAD Ggi P,Q, Mian BT, thay ddi each bieu thi, cac mdi Ken quan gii?a cac luotlatrung diem cua BD,CE,CB du kien cua BT Dd cung la each thay the BT da chd ^a) SosanhBEvaCD.Xaedjnhgdcgiua haidoan bing mgt BT tuong duong vdi nd, nhung don gari thing dd hoae quen thugc vdi HS han Mat khac, neu GV rail luyen cho HS cdthdi quen nhin BT dachodudinhieiif b) Tam giae PMQ vudng can Nhan xet 3: Td ba BT tren, ta ml BT long gdc khac se gii^ cac em tim nhieu each giar qual sau: eho cung mdt BT Qua dd ren luyen tu llnh \\o^ ST^.-Dung phia ngoai tam giac ABC cho tmdc sanglaoehoHSkhihgctoan Cach lam trencijiggiiipf, eae tam giac vudng can tai A la CAE va BAD Ggi P, ren luyen tinh nhuan nhuyin cua TDST cho HS Q, M lan lugt ia trung diem cua BD,CE,CB Chdng Vidu: Cho tam giac ABC vuong tai A co dudwd5 minh ring: a} BE = CD va BE CD; b) Tam giac '.?i cao AH.Chung m t n h ^ = - ^ { ) PMQ vudng can ^W/!an;feM.'Tu BT4cholhay, neugglN la giao diem cua MP va BE, L lagiao diem cua MQ vaCD, de dang suy tugiae NILM la hinh chunhat Do dd, HS cd the thay ke't luan a) va b) eua BT b^ng cac cjiu hdi khacva thu dugc BT flr5;Dungra phia ngoai tam giac ABC cho tn/dc cac tam giac vudng can tai A la CAE va BAD Ggi P, Q,^M lan lugt la trung diem cuaBD,CE,CB; Nia giao diem cua MP va BE, L la giao diem cua MQ va CD Chung minh tu-giac NILM la hinh chanhat Nhanxet5:Mo\6\eu kien coban cua BT la eae tam giac CAE, BAD vudng can tai A nhung dieu kien Hudngdan: Cach I: (1)AB.AC=AH.BC nen BT cdthe dugc phat bie'u lai nhusau: "Cho tam giac ABC vudng tai A Chiing minh ring tich haleanhgdc vuong bang tieh dudng cao nhan , ;• vi^c^nh huyen' Jd day,!digiaiBTtrdnen hien nhien (/)/h/j 5) Cach 2: Vide chung minh PT (1) tuong duong vdi Chung minh AAHB Hinh 'tjci'Jtf 501 Tap chi Gido due so 314 -(ki 2-7/2013) ddng dang vdi ACAB nen BT cd the duge phat bie'u T&i li^u tham khao ttieo each khac Vho tam giac ABC vudng tai A ed I Ho^ng Chiang R^nluy^n khd n3ng sdng tao toan dudng cao AH Chdng minh tam giic AHB dong dang h^c d- trtrdng ph^ thdng NXB Gido due H 1969 vditamgseCAB" Vfl Duong Thuy {chu bidn) Thirc hinh giai toan Cach 3;Vi|cchung minh PT (1) luong duong vdi (giao winh d&o I90 hpc sinh irung hgc co so h? cao chung minh AAHC ddng dang vdi ABAC nen BT cd dang supham) NXB Gidoduc, H 1999 the dugc phat bieu each khac Vho tam giac ABC Dang Quang Viet Ren luyCn tirduy sdng tao thOng viiong tai A, cd dudng cao AH Chdng minh tam giac qua xfly dung he thflng bai tflp NXB Gido dtfc, AHC dong dang vditam giac BAC H 2007 BT Chung minh hai tam giae dong dang da quen SUMMARY thugc vdi HS,do doHS de dang chung minh duoc ket Creative thinking is the most fundamental requaBT source of individuals, the essence of personal crea3)Lua chpn cdng cu thich hop degiaiquyet tivity and the basic purpose of education.Fostering BT Phan tieh gia thiet da eho cua BT mdt each hop creative thinklngin students needs carryingout in li se giup chung ta cd dugc djnh hudng dung dan organic relationta other intellectual activities and cho Idi giai BT Net khdng cd nhung phan tich, djnh throughout the process of leaching However In reality teaching geometry faces many difficulties, hudng dung thi nhieu khi, ta se khdng Ihu duge Idi teachers have not yet paid enough attention io engiai morg mud'n NhiJng BT dang ed tac dung courage students' creative thinking, and many are ren luyen tu logic, su linh hoal, sang tao confused about choosing contents and practical methods.This article summarizes some critical ishoc lap cho HS sues in creative thinking, thus, proposing the use Nhflng BT hinh hgc so cap ndichung ludn ed nhilu of 8'" - grade geometric problems for fostering the carfi giai- Vi vay, lam loan, HS chua nen thoa man creative thinking of secondary school students in vdi mdt ldi giai nao dddudd la Idi giai hay ma can phan conjunction with other intellectual activities: some tich dekhaiftiae dugc cac dac diemriengcua gia thiet solutions suggested hythe author include: Develop and promote new problems from previous ones or cung nhu kdt luan; tudd ed duoc sulien ludng vdi cac from solutions of previous ones, approach given kie'n thuc cu, xual hien ytudng mdi tim Idigiava ehu problems in different ways, choose adequate meansfor solving problems y den sudanh gia cac Idi giai dd.Q Nhirng yeu to cv ban •- ' (Tiep Iheo trang 28) lao dgng ndng nghiep phai gdp phan hinh sunang ddng nghe nghiep, linh kien tri hgc t£^3, tinhfliandoan kel, hda ddng vdi SV eae DT khae Ngoai nhihg yeu tdehu quan va khaeh quan cd anh hudng tich cue, edn cd mdtsd yeu id anh hucng tieu cue den tinh each cua SVDTDao.Dieu kien dia Ii, kinh tekh_d khan dan den mgt sd lap quan, tln^ngudng lac hau vln Ion tai, tinh bao thu quan diem sdng, qua coi trgng cac gia In tmyen thd'ng, qua de cao linh cdket cgng ddng ma chua manh dan tham gia cac hoEfldgng xahgi, da khien SVDT Dao phan nao cham thich ung vdi cac dieu kien sdng mdi Trong giao tie'p, SVDT Dao ngai chd ddng ngudi va thudng thieu tinh ch&dgng nen tn/dc Idp, tn/dc dam ddng hothudng njt re.Trong hoc lap, hgehua the hien rdtinh can eu, chju kho,cham thich ung Irong viec phdihgg hoalddng hgc tap, thudng trdng chd vao suhudng dan, kich thich iCf phia giang vien Nhung han che anh hudng ration d^tich each cua SVDT Dao Do dd,nhatnrong, cac Id' chuttrongnhatnrdng.giang vien can chu ytd'ehuc eac (ki2-7/2013)- hoat ddng phong phii va da dang nh&m kich thich tinh manh dan, tich cue giao tiep, tinh can cii, chju khd hgc tap cua SVDT Dao.Q Tai li^u tham khao VQ DQng Tamil h(jc dan toe NXB TCr diin bdeh Ichoa H 2009 Q6 Vigt Ddng - NguySn Kh^c Tung - NOng Trung • Nguyin Nam Tiin Nguoi DaoffViet Nam rJXB/^Aoa hpc xa hdi, a 1971 Do Huy LSI s6'ng dSn toe va hien dai - may vAn di U lufln vi thirc ti^n NXB Vdn hOa thdng tin H 2007 SUMMARY There are many factors affecting the character of the Dao ethnic minority students, including subjective factors and objective factors Subjective factors Including knowledge capital self-culUvaUon Objective factors including: family education: school education; Dao ethnic culture: the interference ofthe traditional culture ofthe Dao ethnic with the values of modem culture: the process of exchange: the intention with other ethnic groups and industry practices Theseare the basic elements that have the most influence on the formation ofthe character ofthe Dao ethnic minority students Tap chi Giao due so 314 51 ... BT6lai tuBT duge phat bieu nhusau: ggi y cho HS mgt each khac dd'' khai fi7''2.''CholamgiacABC(cdA 90° Ta BADG va CAEF vaquy BT ve BT i£J cd BT tuong tuvdi hai BT tren: 2) Nhin BTda cho dudi goc dp khac vdi BT Br3 ;Cho'' tam giacABC (cd... tam giac ABC cho tmdc sanglaoehoHSkhihgctoan Cach lam trencijiggiiipf, eae tam giac vudng can tai A la CAE va BAD Ggi P, ren luyen tinh nhuan nhuyin cua TDST cho HS Q, M lan lugt ia trung diem