Question

if a b and c are the interior angles of triangle A B and C then show that cos B + C/ 2 is equal to sin A/2​

Answer 1

Step-by-step explanation:

As they are the angles of a triangle,

A+B+C=180

B+C =180 - A

(B+C)/2 =90-A/2 [dividing by 1/2]

Applying cosine on both sides ,

Cos([B+C]/2) = Cos(90-A/2)

Cos([B+C]/2) =Sin(A/2) [cos(90-A) =sinA]

Hence proved.

Answer 2

Answer: Hope this helps

Step-by-step explanation: