Question

Show that,
sin A/2 + Sin B/2+ sin C/2 =1+4 sin(B+C)/4.sin(C+A)/4.sin(A+B)/4
first question
help it brothers n sisters​

Answer 1

formula used are sin theta = cos (90-theta)

cos a -cos b = 2 sin a+b/2 sin b-a/2