[''''FIILraPIUP HIT DO\C KIE\ Tlilt \ B l Oi\li i i m c m HOAT m GIAI HUYET l i \ DE TRÔ G M H i lii\ll HOC Kli''''G G1A\ 6 TRUNG HOC PHO THONG GS TS DAO TAM* 1 Khi dung tn/dc mdt van de ndi ehung, mdt bai[.]
['FIILraPIUP HIT DO\C KIE\ Tlilt \ B l Oi\li iimc m HOAT m GIAI HUYET l i \ DE TRO^G M H i lii\ll HOC Kli'G G1A\ TRUNG HOC PHO THONG GS TS DAO TAM* Khi dung tn/dc mdt van de ndi ehung, mdt bai toan hinh hpc ndi rieng, hpc sinh (HS) can phal biet each tra Idl eac cau hdi sau: - Dua tren CP sd nao de h/a chpn dung cac tien de 'Iri thue da bief nhim giai quyet van dedat ra; - Huy dpng kien thdc nao de van 6$ dupe giai quyethpp li, don gian i]hat; • Caeh bien iSi vS'n de nhu the nao de cd the de dang huy ddng cac kien thuc da biet quatrinh giai quyet vain de datra.^ Be tra Idl cac cau hdl tren, ehung ta ed the khai thac tu tudng su phgm cua G Polya hoat dpng tim tdi \di glai cac bai toan Tuy nhien, cho den vi|ic nghien cdu cu the cac phuong phap huy ddng kien thuc nh^m gitjp HS giai quyet eae van de dgy hpe hinh hpe khdng gian (HHKG) mdt each chu dpng, tich cue, sang tao ehua dupc nghien cdu can ke,h$thd'ng.D3cbi§t,chuaquanjam nghien cdu cac phUdng phap huy dpng diing d^n cac kien thuc ed v§n dyng tu tudng cua li thuyet day hpc hieti dai, tu tudng eija tam li hpc nhan thde va chua khac phue dupc nhdng khd khSn, sal lam^cua HS chuyen tu vi$c nghien cdu hinh hoe phang sang nghien cdu HHKG Mue tieu nghien cdu bai viet la de xua't cac phuong phap huy ddng kien thue theo hudng dd'i m6< phuong phap day hpe, dae biet la dinh hudng tiep cSn phat hien nang It/c glai quyetvande cho HS,kh§c phi^c nhi>ig khd khdn, sai lam cua cac em hpc tap HHKG dtrung hpc thong (THPT) V i ^ nghien cdu, de xuait eae glai phap dua tren m$ts6eosdli luan ehuyeu sau (dupc phan anh cac cong trinh nghidn cijru cua cac tac gia: Nguyin Ba Kim;lu.M.Koliagln; A N Lenonchiev; Phan Trpng Ngp; G Polya; Dao Tam): - Kha nang lua ehpn dting eac tiln de eho lap luan giai quyet van de, dd, tien de dupc hie'u la: cac tien de, menh de da chthig minh, cac khai niem da biet; - Luan diem vevaiUdcua tri thuc, dae biet la tri thuc phuong phap vi/a la cfieu ki^n, vda la mtjc tieu eua hoatdpng; - Cai mdi thudng dupe phat hien thdng qua viec ehuyen hda cae lien (kll-412013)- tudng tdddi tupng sang ddi tupng khac Ngoai cac co sd li luan cae blen phap de tren eo sdtht/c tiln khao sat nhdng khd khan, sai lam cua HS Dudi day, ehung tdi trinh bay mpt so phuong phap huy dpng kien thdechu yeu khiday hoc HHKG dtrudng THPT Phuang phap Luyen tap eho HS xac djnh tri thuc coi ngudn cua tri thue can tim an chua cae van dedua nham dinh hudng dung cho cac boat dgng xam nhap vao dd) tugng nghiin euu Viec xae dinh cac tri thdc edi ngudn de lam sang to quan he nhan qua gida tri thue da bietva tri thue can tim; eac tri thdc cdl nguon ddng vai trd djnh hudng, dieu chinh hoatdpng xam nhap vao ddi tupng lam sang td cac dd'i tupng toan hpc, cac quan he can kham pha Dd la eP sd de HS hoat ddng chiem finh kien thdc Phuong phap cd the thuc hien day hpc cac djnh li, quy t^c va day hpc giai eac bai tap toan Giao vien (G V) cd the xay dung he thd'ng cac cau hdi supham,giup HS huy ddng kien thuc va djnh hudng hoatdpng glal quyet van de Vidu /.-Cho hinh lap phuong ABCD.A,BjC,D, Gpi cac diem M; N; P lan lupt la trung die'm cua cac eanhAD;BB,;C,D,.Haydt/ngthietdlencuahinhlap phuong tao bdi mat phing (M NP) Khi giai baitoan nay, HS gap khd khan viec xac dinh giao cua mat phang (MNP) vol mdt mat eua hinh lap phuong de td xac dinh giao cija mat phang vdi cac mat edn lai Trithuc edi ngudn can chua'n *Tni0ng Dai hoc Vinh Tqp chi Gido due SO 307 | 51 bj eho HS gdm: - Quy trinh tim giao fijyen cua hai matphang;-Quytrinh tim giao cuamptdudngthSng vtifi mdt mat phang; - Cach xac dinh mat ph&ng: mat phang di C|ua ba diem; mat ph|ng xac djnh bdi hai dudng thang edt nhau; mat phing xac dinh bdi hai dudng thang song song; mat phdng ehua iiidt dudng thang va mot diem khdng thupc dudng thang Td dd, HS cd the huy dpng kien ttidc thdng qua hethd'ng cau hdi G V dat ching han nhu: - Neu quy trinh dt/ng giao cua dudng thang^MN vdl mat phang (A,B,C,DJ; -Xac djnh mat phing (a) chda MN, la mat phang chda hai dudng song song BE, va MM,, M, la trung diem eua canh A,D,; Xacdinhglaotuyen cua mat phing (a)vtiflmat phang day(A,B,C,D,),ddladUdng thing B M , ; - T r o n g mat phang (a), xac djnh giao diem S cua dudng thing MNvaB,M, GV yeu eau^HS xac dmh giao cua mat phing (MNP)vamatphing (A,B,C,D,)cuahinh lap phuong Nhd cac kien thuc da biet, HS tim dupc giao la doan PQ (xem hinh /) Cae giao diem cdn lai HSed the tu xac djnh nhd he thdng kien thdc da biet va tim dupc thiet dien la lye giae deu MTNQPR; d d Q , R , T lan lupt la trung diem cac canh B,C,; D,D va AB Phuang phap 2: Chuyin viec nghien cuu, tim tdi cac tinh chat eua hinh khdng gian qua viec nghien ct/u tinh chat bg phan hinh hge phing, tu huy dgng kiih thue da biet hinh hgc phang degiai quyet yah de cila hinh khdng gian Phuong phap nham tao si/ ket nd'i gida viec hoc tap, nghien euu HHKG vdi kien tht/c hinh hpe phang da biet, tranh st/dt/t quang ve phuong dien tam li cua HS HS nghien cuu hinh hpe theo phuong phap la eo hdi de tiep can, phat hien each gial quyet cac bai toan khdng gian nhd viec chuyen hda each gial cua bai toan H H KG ve bai toan phang Ching han nhu: - Chuyen bai toan tim tam va ban kinh mat cau ve bai toan tim tam va ban kinh eua dudng trdn Idn mpt mat phang xae djnh di qua tam; - Chuyen hda bai toan quy tich khdng gian ve baitoan quy tieh mat phang; - Chi/ng minh mpt dinh lieua HHKG dupc chuyen vevan dyng djnh li da biet mat phing GpiO la tmng diem ctja doan thing AB, khidddo tl s d ' ^ = - ^ nen cac diem va thupe mat phing (a)di qua va (a)song song vdi cae dudng thang a va b Dieu suy tudjnh li Thales dao khong gian HS dl^dang chdng minh dupc I la tnjng diem cua doan thing M,N,, d d M , ; N , lan lupt la cac hinti chieu cua M; N len mat phing (a) theo phuong chieu AB, Tudd suy duoc quy tieh can tim Vidu3:Qho tddien OABC cd gdc tam di?n dinh la gde tam dien vudng.Vedudngeao GHctjatudien.Gpil la tmng die'm cua doan OH; ki hieu Sj,; S^j S^; S^ lan lupt la dien tich eua cae mat ddi dien vd^ eae dinh 0;A;B:C Chdng minh ring:s/,7o+5]M+5j7s+5,'.7c = Baltoan dupegialduatren ketqua bai toan phing sau: 'Cho tam giac ABC vudng tai A Vedudngcao AH Ggi I la tmng diem doan AH Chdng minh ring ° f l ' Z i + A'7s + c ' c ==d" van dyng vao haitam giac vudng ADM vudng tai ; ed dudng eao OH va tam giac vudng BOC vudng tai , cd dudng cao OM, vdl M la giao cua AH vdl BC {hinh 2) Phuang phap 3: Luyen tap cho HS chuyen hda cac lien tudng tudoi tugng sang doitugng khac nhdm cau true lai hinh thuc va ngidung cda van decan nghien cuu dedi dang xac lap m oilien hivdikiih thucdabiit, tudd huy dgng dung din cac kiih thuc degiai quyet van de Phuong phap giup HS khie phue khd khSn ehua xac lap dupc md'i lien he gida dd'i tupng can kham pha vdi cac kien thue da ed; giup HS blen dd'i thong tin an cht/a vain de can giai quyet, biet xem xet cac van de eua HHKG theo nhieu each khae va ren luyen tuduy linh hoat cho cac em viec phat hien cae each gial quyet van de V/'di/4.Cho hinh lap phuong ABCD.A,B,C,D, Gpi la tam cua hinh Sau day.ta xet eae bai toan HHKG nhd st/dung lap phuong Dt/ng thiet kien thuc hinh hpc phan^ da biet dien eua hinh lap Vidu 2:Cho hai dudng thang cheo a va b phuong tao bdi mat Gpi A; B la cac diem CO dinh lan lupt thupc cac dutifng phing (a) di qua O v a thSng a; b Cae diem M; N lan lupt di dpng tren a, b, (a)vudnggdcvdiACj cho AM = BN Tim quy tieh tmng die'm I eua doan Neu dyng true tiep thing MN thiet dien eua hinh lap 521 Tap chi Giao due so 307 -(kil-4/2013) plii/ctng tao bdi mat phSng (a)lhi HS gap kho khan xac djnh qao cua (a)vcncac malcOa hinh iap phi/ong GV c6Ihe luyen tap cho HS chuyen »iec xac (Jinh thiet dien vuong goc veviec xac djnh thiet dien teo b i j mat phang diquaOvasong song vaihaimatphang(BDA,) va (CB,D,) nhd lien tudng cac mat phang lan lifot vuong goc vdi di/dng cheo AC, tai cac diem HvaG Khi dd, la tnjng diem cua doan HG Vjn dung kien thdc ve djnh ti Thales dao dechungtdthietdiendiqua tnjng demcaccanhBC;BB,;A,B;A,D,;DD,:DC(/j//i/j3) Phuang phap 4- Khao sat, nghien cm cac dang sal lim cua HS khiday hgc HHKG va lao ca hgi sua chua sai tam cho cac em qua trinh huy dgng liien thuc giai quyet van dedat Ivlot sddang sai iam thudng gap cua HS day hpc HHKG dd la:-Do chudng ngai sir pham chuyen tir hpctap hinh hpc phjng sang H HKG ;• Do khdng giai quyet can ddi quan he gida cu phap va ngu nghTa; - Do khdng n^m vung djnh nghTa cac khai niem va quy t^c: • Do HS thieu cac bie'u tucfng khdng gian, l u khong gian cdn yeu Xet «i du sau ve sai lam cua HS khdng nam dupc cac djnh nghla tuong duong va thieu kha nang hinh dung hinh khdng gian qija hinh bieu dien Wdu5;Cho hai dudng thing cheo a, b va mpt diem _M khdng thupc cac dudng thing dd Dung dudng thing qua M va cSt cac dudng thing a va b Vdi bai toan nay, cd HS da thuc hien theo quy Irinh: dung m j t phang (a)qua M va dudng thing a; dung mat phing (P) qua M va dudng thing ID Sau dd, HS dua ket luan: giao tuyen cua matphSng(a) va C/? M dudng thing can dung Sai lam d day la H S chua xel tdi cac dieu kien de tdn tai giao luyen Chang h^n, tiong trudng^hop neu diem M va dudng thanfl a nam tren mSt phang (P) song song vdi dudng Ihang b Ihi khdng Ion tai dudng Ihang can di/ng GV can can nhic va siia chda nhung sai lam, thieu sdt cua HS dp khdng n i m virng vi tri tuong dd'i gida cac dudng thing cheo khdng gian Trong pham vi bai viet nay, ehung tdi chi trinh bay boh phuong phap huy dpng kien thuc nham djnh hudng, dieu chinh hoat dpng giai quyet van de cho HS Irong day hpc HHKG d Irudng THPT Cac bien phap cd the van dgng vao day hpc cac npi dung loan hpc khac dcae cap hpc khac Ddc gia can quan lam them phuang phap xem xet cac linh chat hinh hpc bat bien qua cac anh xa, dae biet ia phep bien hinh de lua chpn dung Iri thdc giai quyet van detrongdayhpcHHKG.a (Xem Hep ^ng 55) Giao due hch sir dja phirong (Tiep theo trang 50} tra, danh gia qua trinh hpc va day nhim xac dinh ket qua nhan thdc cua HS va hieu qua day hoc cua giao vien Tddd, cd nhung dieu chinh bd'sung kjp thdi ve npidung va phuong phap Can da dang hda cac hinh thuc tuyen truyen tmyen thd'ng LSDP qua nhieu hinh thuc phong phu nhu: xay dung cac phdng tnjyen tfiong nha tnj'dng; toehue eae hdi thi tim hieu ve LS; suu tam va trien lam tranh anh, tu lieu; eham sdc di tich LS; day manh phong trao dpc sach LS tai tn/dng va nhan dan; tuyen truyen ca khtjc each mang va eae hoat dpng van hda van nghe khac DongThap Mudi la vung dat giau tiem nang Nhan dan Dong Thap Mudi anh dung dau tranh chdng giac ngoai xam va can etJ lao dpng san xuat Vung dat da tao nen mdt tmyen thd'ng dep eho dja phuong va dan toe Tim hieu, luu tru, tieh cue tuyen tmyen, giao dtJC gia tri tmyen thd'ng cua vung Dong Thap Mudlchocac the heHSIatraeh nhiem cua nganh giao dtjcva nhung ngutlfi nghien cuu LS Trong dd nha tn/dng phd'thdng, cae glaovien/.Sdwig vaitro tn/c tiep mang kien thucden cho HS;tung budc giup cae the he HS hieu sau sic hOn que huong, tran trpng nhung qua cua dja phuong minh de khdng ngi/ng hoc tap, tich eye tham gia lao ddng san xuat gdp phan lam giau dep que huong dat nudc.Q Tai lieu tham khdo Ban Ch^p h^nh Dang bO tinh Ddng Thap Ljch sii Dang ba tinh Ddng Thap lap Ban Tuyfin giao Tinh uy NXB Ddng Thdp 1997 H6i Khoa hoc Ljch sdD6ng Thap Dia danh lich si> - V3n hoa huyen Thap Mu6i NXB Ddng Thdp 2012 Pham Chi NSng Dieu Ira, nghien cihi, bien soan tai lieu day hoc Lich sd va Dja li dia phmmg tinh Ddng T h i p tap 1, t^p NXB Ddng Thdp 2004 Trdn Thj Kiem "Sudung tai lieu ljch sd dia phircmg day hoc Lich sd Viei Nam d iruong irung HQC thOng Tap chi Ddng Thdp Xua vd Nay, s6 36/ 2012 SUMMARY The education and historical researchers have a big responsibility In searching, keeping, propagating and educating Uie traditanaJ value of Dong Thap Muoi for Oie pupils High-schools play a direct rolein bringing the knowledge to the pupils On the basis of Uie actual situation, this article focuses on some of possible solution to improve the etfection of this action Tap ehi Giao due so 307 | 53 (kil-4/2013)- ... lupt la trung diem cac canh B,C,; D,D va AB Phuang phap 2: Chuyin viec nghien cuu, tim tdi cac tinh chat eua hinh khdng gian qua viec nghien ct/u tinh chat bg phan hinh hge phing, tu huy dgng... tucfng khdng gian, l u khong gian cdn yeu Xet «i du sau ve sai lam cua HS khdng nam dupc cac djnh nghla tuong duong va thieu kha nang hinh dung hinh khdng gian qija hinh bieu dien Wdu5 ;Cho hai dudng... dudng thing cheo khdng gian Trong pham vi bai viet nay, ehung tdi chi trinh bay boh phuong phap huy dpng kien thuc nham djnh hudng, dieu chinh hoat dpng giai quyet van de cho HS Irong day hpc HHKG