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

If A + B + C =180^@ , prove that : cos^2 A+ cos^2 B-cos^2 C= 1-2 sin A sin B cos C .

If A+B+C=90^(@) then cos^(2)A+cos^(2)B+cos^(2)C=2+K sin A sin B sin C then K=

If DeltaABC , prove that: a) sin^(2)A+sin^(2)B-sin^(2)C=2sinAsinBcosC b) cos^(2)A+cos^(2)B-cos^(2)C=1-2sinAcosBsinC c) cos^(2)A+cos^(2)B+cos^(2)C=1-2cosAcosBcosC

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

If A+B+C= (pi)/(2) ,prove that: (i) cos^(2)A+cos^(2)B+cos^(2)C=2+2"sin"A "sin"B "sin"C (ii) "sin"^(2)+"sin"^(2)B+"sin"^(2)C=1-2 "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.

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

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 =pi/2 , prove that : cos^2 A +cos^2 B+cos^2 C= 2+2 sin A sin B sin C .

cos2B + cos2A-cos2C = 1-4sin A sin B cos C