" (iv) If "b+c=2a cos(B-C)/(2)," then prove that "A=60^(@)

In any Delta ABC, prove that : If b+c=2a cos((B-C)/(2)), then prove that A=60^(@).

In any DeltaABC , prove that : If b+c = 2a cos ((B-C)/2) , then prove that A=60^0 .

In a Delta ABC,/_A=60^(@), then prove that b+c=2a cos[(B-C)/(2)]

If in a Delta ABC, c(a+b) cos B//2 = b(a+c) cos C//2 , prove that the triangle is isosceles.

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 are angles in a triangle, then prove that sin ^(2)A+ sin ^(2)B+sin^(2)C=2+2 cos A cos B cos 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=180^(@) then prove that cos^(2)A+cos^(2)B+cos^(2)C=1-2cosAcosBcosC

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