Saved Bookmarks
| 1. |
If (a+b+c)(b+c-a)=3bc,show that A=60°. |
|
Answer» (b+c+a)(b+c-a) =(b+c)2 - a2 = 3bc b2 + c2 - a2 = bc (b2 + c2 - a2)/2bc = 1/2 So, Cos A = 1/2. (Cosine rule) So, A = 60 |
|