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

If f,g,h are internal bisectoirs of the angles of a triangle ABC, show that 1/f cos, A/2+ 1/g cos, B/2+1/h cos, C/2= 1/a+1/b+1/c

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0

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

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 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)

In a triangle, if the angles A , B ,a n dC are in A.P. show that 2cos1/2(A-C)=(a+c)/(sqrt(a^2-a c+c^2))

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