If `A+B+C=180^0`, prove that : `cos^2( A/2) + cos^2( B/2) + cos^2(C/2) = 2+2 sin(A/2)
Channel: Doubtnut
Date: 2020-04-12

If `A+B+C=180^0`, prove that : `cos^2( A/2) + cos^2( B/2) + cos^2(C/2) = 2+2 sin(A/2) sin( B/2)  sin( C/2)`