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 and C are the angles of a triangle, then |[-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]|

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

If A,B,C are the angles of a triangle, show that, (iii) (cos A cos C + cos (A + B) cos(B + C))/(cos A sin C - sin (A + B) cos (B + C)) = cot C .

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

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)

In triangle ABC , prove that (1) a=b cos C+c cos B (2) b=a cos C+c cos A .

(cos A-cos B+cos C+1)/(cos A+cos B+cos C-1) =