Question

If a, b&c are interior angle of a triangle ABC then show that.
Sin(B+C)/2=cosA/2

Answer 1

Answer:

in a triangle ABC

angle A+ angle B + angle C = 180°

angle B + angle C= 180 - angle A

taking LHS

sin(B+C)/2

sin( 180- A)/2

sin(180/2 -A/2)

sin(90-A/2). ( sin90 -Q = cosQ)

cos(A/2)

Answer 2

Answer:

hope it helps u.............