Question

упростите выражение sin альфа (sin альфа1-cos альфа -1tg альфа)

Answer 1

$sin alpha ( frac{sin alpha }{1-cos alpha }- frac{1}{tg alpha })=sin alpha (frac{sin alpha }{1-cos alpha }- frac{cos alpha }{sin alpha })=\\= frac{sin alpha (sin^2 alpha -cos alpha (1-cos alpha ))}{sin alpha (1-cos alpha )}= frac{sin^2 alpha -cos alpha +cos^2 alpha }{1-cos alpha } = frac{1-cos alpha }{1-cos alpha }=1$