Show that
`2"sin"^(2)beta+4 cos(alpha+beta)"sin" alpha sin beta+cos2(alpha+beta)=cos 2alpha`.

2sin^(2)beta+4cos(alpha+beta)sin alpha sin beta+cos2(alpha+beta)=

Prove that 2sin^(2)beta+4cos(alpha+beta)sin alpha sin beta+cos2(alpha+beta)=cos2 alpha

Simplify 2sin^(2)beta+4cos(alpha+beta)sin alpha sin beta+cos2(alpha+beta)

2sin^(2)beta+4cos(alpha+beta)sinalphasinbeta+cos2(alpha+beta)=?

Show that: sin^2 alpha + sin^2 beta + 2sinalpha sinbeta cos(alpha+beta)=sin^2 (alpha+beta)

If cos alpha+cos beta=0=sin alpha+sin beta then cos2 alpha+cos2 beta=

sin ^ (2) alpha + cos ^ (2) (alpha + beta) + 2 sin alpha sin beta cos (alpha + beta) = (i) sin ^ (2) (alpha) (ii) sin ^ (2) (beta ) (iii) cos ^ (2) (alpha) (iv) cos ^ (2) (beta)