✔ 最佳答案
(side opp. eq. ∠s)呢個reason相信大家都有讀過…
只係冇人諗住prove d 咁簡單既rule姐…
triangle ABC is an isos triangle,where AB=AC
let M be the mid point of BC,ie BM=MC
produce line AM,
in Triangle ABM and ACM,
AB=AC(Given)
BM=MC(mid-pt)
AM=AM(Common)
∴⊿ABM congruent with ⊿ACM
then ∠ABM=∠ACM(corr. ∠s,congruent ⊿)
QED
2007-08-24 16:00:01 補充:
another triangle XYZGiven ∠XYZ=∠XZY,prove XY=XZLet a be XY,b be XZ∵∠XYZ=∠XZYthen sin∠XYZ=sin∠XZYa/(sin∠XZY)=b/(sin∠XYZ) (by sine law)a=b (sin∠XYZ=sin∠XZY)XY=XZQED
2007-08-25 21:29:21 補充:
我最上面個個proof係
http://hk.knowledge.yahoo.com/question/?qid=7007082402751既,中間補充個個proof先係頁既問題
2007-08-25 21:32:16 補充:
我最上面個個proof係已知兩邊等,求兩角等中間補充個個proof係已知兩角等,求兩邊等希望你識睇英文proof啦=]