Question

упростите выражение (ctg2a + 1)*sin2a-cos2a

Answer 1

(ctg2a + 1)*sin2a-cos2a = ((cos2a/sin2a) + 1)*sin2a-cos2a =
((cos2a + sin2a) /sin2a) * sin2a-cos2a = sin2a.

Answer 2

$(ctg2 alpha +1)*sin2 alpha -cos2 alpha =$
$= frac{cos2 alpha }{sin2 alpha }*sin2 alpha +sin2 alpha -cos2 alpha =$
$=cos2 alpha +sin2 alpha -cos2 alpha =sin2 alpha .$