Question

Q=>If A, B and C are interior angles of a triangle ABC, then show that sin [(B + C)/2] = cos A/2​

Answer 1

Step-by-step explanation:

A+B+C=180

B+C=180-A

B+C/2=90-A/2

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

Sin(B+C/2)=CosA/2