If `A, B, C` are the angles of a right angled triangle, then `(cos^2A+ cos^2B+ cos^2C)` equals

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

If one of the angles A,B,C of a triangle is not acute, show that cos^2A+cos^2B+cos^2C=1

If A,B,C are angles of a triangle, then 2sinA/2cos e c B/2sinC/2-sinAcosB/2-cosA is

If A,B,C are angles of a triangle, prove that cosC=-cos(A+B) .

If A, B and C denote the angles of a triangle, then Delta = |(-1,cos C,cos B),(cos C,-1,cos A),(cos B,cos A,-2)| is independent of

If A,B,C are the angles of triangle ABC, then the minimum value of |{:(-1,cos C , cos B),(cos C , -1, cos A ) , (cos B , cos A , -1):}| is equal to :

If A, B, C are interior angles of DeltaABC such that (cos A + cos B + cos C)^(2)+(sin A + sin B + sin C)^(2)=9 , then number of possible triangles is

If A,B,C,D are the angles of a quadrilateral, prove that "cos"1/2(A+B)+"cos"1/2(C+D)=0 .

if A, B and C are interior angles of a triangle ABC, then show that cos((B+C)/2) = sin (A/2)

if A, B and C are interior angles of a triangle ABC, then show that cos((B+C)/2) = sin (A/2)