Question

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

Answer 1

Hi

Your Answer friend,

➡ We know,

Sum of the interior angles of a triangle is

==> 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............{Hence, Shown}

Hope it helps you

Answer 2

In triangle ABC

A+B+C=180° (ASP)

B+C=180°-A

Dividing the above equation by 2

As shown below in image