If`A+B+C=3pi/2` then `cos2A+cos2B+cos2C=1-4sinAsinBsinC`

If A+B+C=pi , then cos 2A+cos 2B+cos 2C=

In triangleABC,A+B+C=pi ,show that cos^2A+cos^2B-cos^2C=1-2sinAsinBcosC

In triangleABC,A+B+C=pi ,show that cos2A+cos2B+cos2C=-1-4cosAcosBcosC

If A+B+C=pi , prove that cos 2A +cos 2B +cos 2C=-1-4cos A cos Bcos C.

If A+B+C=(3pi)/2 . Then cos 2A +cos 2B+cos2C is equal to ................. A) 1-4 cos A cos B cos C B) 4 sin A sin B sin C C) 1+2 cos A cos B cos C D) 1-4 sin A sin B sin C

If A+B+C =pi, then cos ^(2) A+ cos ^(2)B + cos^(2) C is equal to

In triangleABC,A+B+C=pi ,show that cosA+cosB-cosC=4cos(A/2)cos(B/2)sin(C/2)-1

If A+B+C =pi and cos A = cos B cos C then cot B. cot C = ............. A) 1/3 B) 1 C) 2 D) 1/2

If cos(A-B)=3/5 and tanAtanB=2 then......................... A) cos A cos B=1/5 B) sin A sin B = -2/5 C) cos A cos B =-1/5 D) sin A sin B =-1/5

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