Question

Упростить выражения.1-cosα+cos2α/sin2α-sinα

Answer 1

(1-cosα+cos2α)/(sin2α-sinα)=(2cos²α-cosα)/(2sinα*cosα-sinα)=cosα(2cosα-1)/sinα(2cosα-1)=cosα/sinα=ctgα.

Answer 2

$frac{1-cos a + cos 2a}{sin 2a - sin a}=frac{2cos^2 a -cos a }{2sin a cos a - sin a}= frac{cos a(2cos a - 1)}{sin a(2cos a - 1)} = frac{cos a }{sin a} =\ = ctg a$