यदि `A+B+C=180^(@)` (अथार्त `pi`) तो सिद्ध करे कि
`(cos A)/(sin B* sin C)+(cos B)/(sin C* sin A)+(cos C)/(sin A* sin B)=2`

if A + B + C = pi then (cos A) / (sin B sin C) + (cos B) / (sin C sin A) + (cos C) / (sin A sin B) =

(cos A) / (c sin B) + (cos B) / (a sin C) + (cos C) / (b sin A) =

In Delta ABC, (cos A)/(c sin B)+(cos B)/( a sin C)+(cos C)/( b sin A) =

(b-a cos c)sin A=a cos A sin c

If : A+B+C=pi, "then" : sin 2A + sin 2 B - sin 2 C= A) 4 sin A * cos B * cos C B) 4 sin B * sin C * cos A C) 4 sin C * cos A * cos B D) 4 sin A * sin B * sin C

(2sin (AC) cos C-sin (A-2C)) / (2sin (BC) cos C-sin (B-2C)) = (sin A) / (sin B)

(2sin (AC) cos C-sin (A-2C)) / (2sin (BC) cos C-sin (B-2C)) = (sin A) / (sin B)

(sin(A - B))/(cos A cos B) + (sin (B - C))/( cos B cos C) + (sin(C - A))/(cos C cos A) is

Prove that a cos A+b cos B+c cos C=4R sin A sin B sin C