Question

Сократите пожалуйста дроби:
1) sin2a/2cosa
2) sin2a/sina
3) 2cos^2a/sin2a
4) cos2a/sina+cosa

Answer 1

$1)\ \frac{sin2\alpha}{2cos\alpha}=\frac{2sin\alpha*cos\alpha}{2cos\alpha}=sin\alpha\\\\2)\ \frac{sin2\alpha}{sin\alpha}=\frac{2sin\alpha*cos\alpha}{sin\alpha}=2cos\alpha\\\\3)\ \frac{2cos^2\alpha}{sin2\alpha}=\frac{2cos^2\alpha}{2sin\alpha*cos\alpha}=\frac{cos\alpha}{sin\alpha}=ctg\alpha\\\\4)\ \frac{cos2\alpha}{sin\alpha+cos\alpha}=\frac{cos^2\alpha-sin^2\alpha}{sin\alpha+cos\alpha}=\frac{(cos\alpha-sin\alpha)(cos\alpha+sin\alpha)}{sin\alpha+cos\alpha}=cos\alpha-sin\alpha$