Question

In triangle ABC, (b+c)cos A + (c+a) cos B + (a+b) cos C = [MP PET 1985]

• A. 1
• B. a + b + c
• C. 2(a+b+c)

Answer 1

The correct option is A 1

(b+c) cos A + (c + a)cos B + (a+b) cos C = a + b + c
From expanding and collecting terms using projection rule, a = b cos C + c cos B etc.