Prove that cos (A + B) cos C - cos (B + C)
cos A = sin B sin (C - A)

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 .

If A+B+C=(3pi)/(2) , prove that cos ^(2)A+ cos ^(2) B- cos ^(2)C=-2 cos A cos B sin C.

In /_\ABC ,Prove that a cos A + b cos B + c cos C = 2a sin B sin C

In any DeltaABC , prove that : a cos A + b cos B + c cos C = 2a sin B sin C