" 11."a cos A+b cos B+c cos C=2b sin A sin C=2c sin A sin B

In any triangle ABC, prove that following: quad a cos A=b cos B=c cos C=2b sin A sin C=2c sin A sin B

a cos A + b cos B + c cos C = 2a sin B sin C

a.cos A + b.cos B + c.cos C = 2a sin B sin C

Prove that a cos A + b cos B + c cos C = 4 R sin A sin B sin C.

Prove that a cos A + b cos B + c cos C = 4 R sin A sin B sin C.

Prove that a cos A + b cos B + c cos C = 4 R sin A sin B sin C.

Prove that a cos A + b cos B + c cos C = 4R sin A sin B sin C

Expand cos ( A + B + C). Hence prove that cos A cos B cos C = sin A sin B cos C + sin B sin C cos A + sin C sin A cos B, if A + B + C = (pi)/(2) .

If A+B+C=(pi)/(2) , then prove that cos 2A + cos 2B + cos 2C=1+4 sin A sin B sin C .