[" 15."cos^(2)A+cos^(2)B-cos^(2)C=1-2sin A sin B cos C],[" uf "A+B+C=pi," an Fura "]

cos2B + cos2A-cos2C = 1-4sin A sin B cos 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=180^(@) then prove that cos^(2)A+cos^(2)B-cos^(2)C=1-2sin 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=

cos2a-cos2b + cos2c = 1-4sin a cos b sin 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 = pi, then cos^(2) A + cos ^(2) B + cos ^(2) C is equal to : A) 1 - cos A cos B cos C B) 1 - 2 cos A cos B cos C C) 2 cos A cos B cos C D) 1 + cos A cos B cos C

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

In a Delta ABC, if sin^(2)A+cos^(2)C=cos^(2)B then sin B cos C+cos C sin A is equal to

If A+B+C=(3pi)/(2) , prove that cos ^(2)A+ cos ^(2) B- cos ^(2)C=-2 cos A cos B sin C.