Question

prove that sin b + c upon 2 is equal to Cos A upon 2​

Answer 1

Step-by-step explanation:

a+b+c=180

b+c=180-a

sin(b+c/2)=sin(180-a/2)

=sin(90-a/2)

=cos(a/2)

Answer 2

The perimeter of triangle is a+b+c=180 ...after that we divide it by 2