In a triangle ABC, prove that: `cos^4A+cos^4B+cos^4C= 3/2 + 2 cosA cosB cosC+ 1/2 cos 2A cos2B cos2C`

In a triangle ABC , Prove that sin^4A+sin^4B+ sin^4C=3/2+2cosAcosBcosC+1/2cos2Acos2Bcos2C

In a triangle ABC, Prove that: sin^3A+sin^3B+sin^3C = 3cosA/2 cosB/2 cosC/2 +cos (3A)/2 cos (3B)/2 cos (3C)/2

If A+B+C=pi , prove that : cos2A+cos2B+cos2C=-1-4cosA cosB cosC

If A+B+C=0 , Prove : cos^2 A + cos^2 B +cos^2 C=1+2cosA cosB cosC .

If A+B+C = pi , prove that : cos2A +cos2B +cos2C =-1-4cosAcosBcosC .

If A+B+C=180^@ , then prove that cos^2 A + cos^2 B +cos^2 C=1-2cosA cosB cosC .

If A+B+C=2pi , prove that : cos^2B+cos^2C-sin^2A-2cosA cosB cosC=0 .

In triangle A B C , prove that cos e c A/2+cos e c B/2+cos e c C/2geq6.

If A+B+C=pi , prove that : cosA + cosB-cosC=4cos(A/2) cos(B/2) sin(C/2) -1

For any triangle ABC, prove that a(cosC-cos B)\ =\ 2\ (b - c)\ cos^2(A/2)