If A,B,C are the angles of a triangal ,prove that : cos A +cos B + cos `C = 1+r/R`

If A ,\ B ,\ C are the angles of a triangle, prove that : cos A+cos B+cos C=1+r/Rdot

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 the angles of a triangle then prove that cos A+cos B-cos C=-1+4cos((A)/(2))cos((B)/(2))sin((C)/(2))

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

Prove that a cos A+b cos B+c cos C<=s

If A,B,C are the angles of a triangle, prove that the maximum value of cos A cos B cos C "is" (1)/(8)

IF A,B,C are angles of a triangle , Prove that cos2A+cos 2B+cos 2C=-4cosAcosBcosC-1

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

If A,B,C,D are angles of a cyclic quadrilateral,prove that cos A+cos B+cos C+cos D=0

Prove the questions cos A + cos B + cos C = 1 + (r )/(R )