If three angles A, B, C are such that cos A+ cos B + cos C = 0 and if `lambda cos A cos B cos C = cos 3A + cos 3B + cos 3C`, then value of `lambda` is :

If cos A+ cos B + cos C =0 then cos 3A+ cos 3B + cos 3X

If cos A+ cos B + cos C=0 , prove that cos 3A + cos 3B + cos 3C = 12 cos A cos B cos C

Let A,B and C be three angles such that cos A+cos B+cos C=0 and if cos A cos B cos C=lambda(cos3A+cos3B+cos3C) then find the value of lambda

(a + b + c) (cos A + cos B + cos C)

Assertion (A): If A, B, C are the angles of a triangle such that cos A + cos B + Cos C = 0 = sin A + sin B + sin C then cos 3A + cos 3B + cos 3C = -3 Reason (R) : If cos alpha + cos beta + cos gamma = 0 = sin alpha + sin beta + singamma then cos 3 alpha + cos 3 beta + cos 3 gamma = 3 cos (gamma+alpha+beta)

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

If A+B+C=0 , then prove that cos ^(2)A+ cos ^(2) B + cos ^(2) C =1+2 cos A cos B cos C

if A + B +C= pi/2 ,prove that cos(A - B - C)+ cos (B-C- A) + cos (C- A - B)= 4 cos A cos B cos C