Question

Номер 205,совсем не понимаю эту тему

Answer 1

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Answer 2

$(frac{cos beta }{sin alpha }+frac{sin beta }{cos alpha} )*frac{1-cos4 alpha }{cos( pi - beta + alpha )}=frac{cos alpha cos beta +sin alpha sin beta }{sin alpha *cos alpha}*frac{1-cos^22 alpha +sin^22 alpha }{-cos( alpha - beta )}= \ \ =frac{cos( alpha-beta) }{sin alpha *cos alpha}*frac{sin^22 alpha +sin^22 alpha }{-cos( alpha - beta )}=-frac{2sin^22 alpha }{sin alpha *cos alpha }=-frac{4sin^22 alpha }{2sin alpha *cos alpha }=$
$=-frac{4sin^22 alpha }{sin2 alpha}=-4sin2 alpha$