[" 5.Prove by vector method that "],[qquad cos(alpha+beta)=cos alpha cos beta-sin alpha sin beta]

Prove by vectors that : cos (alpha + beta) = cos alpha cos beta- sin alpha sin beta .

Prove by vectors that : cos (alpha - beta) = cos alpha cos beta+ sin alpha sin beta .

Prove by vector methods that sin(alpha+beta)=sin alpha cos beta+cos alpha sin beta

Prove by vector methods that sin(alpha+beta)=sin alphacos beta+cos alphasin beta

Using vectors prove that sin(alpha - beta) = sin alpha cos beta- cos alpha sin beta .

Using vectors, prove that sin (alpha+beta)=sin alpha cos beta+ cos alpha sin beta .

(sinalpha cos beta+cos alpha sin beta)^2+(cos alpha cos beta-sin alpha sin beta)^2=1

Prove that (sin alpha cos beta + cos alpha sin beta) ^(2) + (cos alpha coa beta - sin alpha sin beta) ^(2) =1.

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

Prove that: cos ^ (2) alpha + cos ^ (2) (alpha + beta) -2cos alpha cos beta cos (alpha + beta) = sin ^ (2) beta