IF A,B,C are angles of a triangle , Prove that `cos2A+cos 2B+cos 2C=-4cosAcosBcosC-1`

If A, B, C are angles of a triangle , prove that cos 2A - cos 2B + cos 2C =1 -4 sin A cos B sin C

If A, B, C are angles of a triangle , prove that cos 2A+cos 2B -cos 2C=1-4 sin A sin B cos C

If A, B, C are angles of a triangle , prove that sin 2A+sin 2B-sin 2C=4cos Acos B sin C

IF A,B,C are angles in the triangle, then prove that cosA+cosB-cosC=-1+4cos""A/2.cos""B/2.sin""C/2

If A, B, C are angles in a triangle , then prove that cos^(2)A+cos^(2)B-cos^(2)C=1-2sin Asin Bcos C.

If A , B , C are angles in a triangle , then prove that sin A + sin B + sin C =4 cos. (A)/(2) cos . (B)/(2) cos .(C)/(2)

If A, B, C are angles in a triangle , prove that sin A+ sin B -sin C =4sin. (A)/(2)sin. (B)/(2) cos. (C)/(2)

If A, B , C are angles in a triangle, then prove that sin ^(2)A+ sin ^(2)B+sin^(2)C=2+2 cos A cos B cos C

If A+B+C=180^(@) then prove that cos^(2)A+cos^(2)B+cos^(2)C=1-2cosAcosBcosC

If A, B, C are angles of a triangle, then prove that sin^(2)""A/2+sin^(2)""B/2-sin^(2)""C/2=1-2cos""A/2cos""B/2sin""C/2 .