- Huongdan • Z'^^^i^J
3) Vegian dovecto bang each van dung quy tac hinh binh han h Phuong phap vec to bupc (vec to chung goc)
Vẹ gian do vec ta theo phuong phap vec to buoc gom cac hu&c nhu sau:
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*Chgn ngang la true dong dien, diem O lam goc.
*Ve ISii luol cac vec-to" bieu dien cac di^n ap, cung chung goc O theo nguyen tac:
+ L - len. + C - xuSng. + R - ngang.
Do dai cac vec-tó ti le vol cac gia tri liieu dung tuolig ling.
*Chi t6ng hffp cac vec-to" dien ap c6 lien quan
den du kien cua bai toan. ^ -., •Bieu dien cac so Ueu len gian dọ
•Dua vao cac he tliijc lutmg trong tam giac de tim cac dien ap hoac goc chuabiet.
Mot sódiem can heu y: ; ,5> , •
Cac dien ap tren cac phan tu* dugc bieu dien boi cac vec to ma chieu dai ti le voi dien ap hieu dung ciia nọ
Do lech pha giiia cac dien ap la goc hop boi gii>a cac vec to tuong ling bieu d i i n chiing. Do lech pha gii>a dien ap va cuong do dong dien la goc hop boi vec to bieu dien no voi true I . Vec to "nam tren" (huong len tren) se nhanh pha hon vec to "nam d u o i " (huong xuong duoi).
Viec giai cac bai toan la nham xac djnh do Ion cac canh va cac goc ciia cac tam giac hoac t i i giac, nha cac he thiic lugng trong tam giac vuong, cac he thuc lugng giac, cac djnh li ham so sin, ham so cos va cac cong thiic toan hgc.
• ,,M . A 'y] tiff J ^rit..
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Trong toan hgc mot tam giac se giai dugc neu biet truoc 3 (hai canh mot goc hoac hai goc mot canh hoac ba canh) trong so 6 yeu tó (ba goc trong va ba canh).
B o t r g k i e n t h ^ c Viit l i L mil l i c n henh VTV2. t^p 2 - Chu VSn B i e n
T i m tren gian do vecto tam giac biet triioc ba yeu to (hai canh mot goc, hai goc mot canh), sau dcS giai tam giac do de tim cac yeu to c h u a biet, c u tiep tuc nhu vay cho cac tam giac con laị
D o dai canh cua tam giac tren gian do bieu thi dien ap hieu dung, do Ion goc bieu thj do lech phạ
Mot so he thiíc l u o n g trong tam giac vuong: i ,
á -~ b' + c
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