If A,B,C are the angles of a triangle then prove that `cosA+cosB-cosC=-1+4cos(A/2)cos(B/2)sin(C/2)`

IF A,B,C are angles in the triangle, then prove that cosA+cosB-cosC=-1+4cos""A/2.cos""B/2.sin""C/2

If A,B,C are angles in a triangle , then prove that cosA+cosB+cosC=1+4sin. (A)/(2)sin. (B)/(2) sin. (C)/(2)

If A+B+C=pi , prove that : cosA + cosB-cosC=4cos(A/2) cos(B/2) sin(C/2) -1

If A+B+C=pi , prove that : cosA + cosB-cosC=4cos(A/2) cos(B/2) sin(C/2) -1

If A,B,C be the angles of a triangle, then prove that , abs((-1,cosC,cosB),(cosC,-1,cosA),(cosB,cosA,-1)) =0

Prove that cosA -cosB -cosC =1-4sin(A/2)cos(B/2)cos(C/2) ,if A+B+C= pi

In triangleABC,A+B+C=pi ,show that cosA+cosB-cosC=4cos(A/2)cos(B/2)sin(C/2)-1

If A+B+C= pi ,prove that :cosA+cosB-cosC=-1+4cosA/2cosB/2sinC/2.

If A, B, C are angles of a triangle , prove that cos 2A - cos 2B + cos 2C =1 -4 sin 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