If `2cos A +3 cos B +5 cos C = 0 = 2 sin A + 3 sin B + 5 sin C` then `8 cos 3A + 27 cos 3B+125cos 3C = k cos ( A + B + C)` then k is

a cos A + b cos B + c cos C = 2a sin B sin C

a.cos A + b.cos B + c.cos C = 2a sin B sin C

If sinA + sin B + sin C=3, then: cos A + cos B + cos C=

If sin A + sin B + sin C = 3, then cos A + cos B + cos C is equal to

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)

If 2cos A+3cos B+5cos C=0=2sin A+3sin B+5sin C then 3A+27cos3B+125cos3C=k cos(A+B+C) then k is

If sin A+sin B + sin C =3, then the value of cos A + cos B + cos C is

cos2B + cos2A-cos2C = 1-4sin A sin B cos C

cos A + cos B + cos C = 1 + 4sin ((A) / (2)) sin ((B) / (2)) sin ((C) / (2))