" (15) "cos alpha+cos beta+cos gamma+cos(alpha+beta+y)

Prove that cos alpha + cos beta + cos gamma + cos (alpha + beta + gamma) = 4 cos"" (alpha + beta)/(2) cos ""(beta + gamma)/(2) cos ""(gamma + alpha)/(2) .

cos alpha + cos beta + cos gamma + cos ( alpha + beta + gamma ) =

If cos alpha+ cos beta+ cos gamma + cos alpha cos beta cos gamma=0 , show that sin alpha (1+ cos beta cos gamma)=+- sin beta sin gamma .

If alpha,beta, gamma are any three angles , then cos alpha + cos beta - cos gamma - cos (alpha+beta+gamma)=

For all values of alpha,beta,gamma prove that: cos alpha + cos beta+ cos gamma+ cos(alpha+beta+gamma) ="4cos"(alpha+beta)/2cdot"cos" (beta+gamma)/2cdot"cos"(gamma+alpha)/2

Express cos alpha + cos beta + cos gamma+ cos ( alpha+beta+gamma) as the product of three cosines.

Prove that cos alpha+cos beta+cos gamma+cos(alpha+beta+gamma)=4cos((alpha+beta)/(2))cos((beta+gamma)/(2))cos((gamma+alpha)/(2))

Prove that: cos alpha+cos beta+cos gamma+cos(alpha+beta+gamma)=4(cos( alpha + beta ))/(2)(cos( beta + gamma ))/(2)(cos( gamma + alpha ))/(2)

If cos alpha + cos beta + cos gamma = sin alpha + sin beta + sin gamma = 0 , show that cos 3alpha + cos 3 beta + cos gamma = 3 cos (alpha + beta + gamma) and

Prove that cos alpha+cos beta+cos gamma+cos (alpha+beta+gamma) =4cos((alpha+beta)/2)cos((beta+gamma)/2)cos((gamma+alpha)/2)