[" 7.If "A+B+C=(pi)/(2)" then "sum(cos(B+C))/(cos B cos C)=],[quad 1)1]

If A + B + C = (pi)/(2) , prove that cos 2A + cos 2B + cos 2C = 1 + 4 sin A sin B cos C

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

If A+B+C=pi then cos((B)/(2))+cos((C)/(2)) equals

If A+B+C=180^(@) , then (cos2A+cos2B+cos2C+1)/(cos A cos B cos C)

If A+B+C=(pi)/(2) , then prove that cos 2A + cos 2B + cos 2C=1+4 sin A sin B sin C .

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

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 A + B + C =pi , prove that : cos A + cos B - cos C> 1 .

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/2 ,prove that cos(A - B - C)+ cos (B-C- A) + cos (C- A - B)= 4 cos A cos B cos C