`cos^2A+cos^2B+cos^2C=1 - cosAcosBcosC` prove that

cos^(2)A+cos^(2)B+cos^(2)C=1-cos A cos B cos C prove that

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

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

If A+B+C=180^0 , prove that : cos^2 A + cos^2 B + cos^2 C + 2cosA cosB cosC=1 .

If A+B=C, then cos^(2)A+cos^(2)B+cos^(2)C-2cosAcosBcosC=

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

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

In a /_ABC prove that cos2A+cos2B+cos2C=-1-4cos A cos B cos C

If A+B+C=180^(@) then cos2A+cos2B+cos2C=1-4cos A cos B cos C 2.If A+B+C=0 then cos A+cos B+cos C=-1+4(cos A)/(2)(cos B)/(2)(cos C)/(2)

If : A+B+C=pi, "then" : 1-cos^(2) A-cos^(2)B-cos^(2)C= A) 2 cos A * cos B * cos C B) 2 sin A * cos B * cos C C) 2 cos A * sin B * cos C D) 2 cos A * cos B * sin C