Question

In a AABC,prove that sin(A+B/2)= cos c/2​

Answer 1

Answer:

A + B + C = 180°

Therefore ,

B + C = 180 - A

(B + C) / 2 = (180 - A ) / 2

(B + C) / 2 = 90 - (A / 2)

Hence R.H.S. :- cos (A / 2) = sin [ 90 - (A / 2) ]

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