Question

2 sin (альфа - 7π) + cos (3π/2 + альфа)/ sin (альфа + π)

Answer 1

$frac{2sin( alpha -7pi )+cos(frac{3pi}{2}+ alpha )}{sin( alpha +pi )}=frac{-2sin(pi - alpha )+sin alpha }{-sin alpha }=\\=frac{-2sin alpha +sin alpha }{-sin alpha }=frac{-sin alpha }{-sin alpha }=1$