Question

cos3a/2sina + 3sina/2cosa

Answer 1

$\frac{cos(3a)}{2sin(a)}+ \frac{3sin(a)}{2cos(a)} = \frac{cos(3a)2cos(a)+3sin(a)2sin(a)}{4sin(a)cos(a)} = \frac{2(cos(3a)cos(a)+3sin^2(a)}{4sin(a)cos(a)} =\\= \frac{cos(3a)cos(a)+3sin^2(a)}{sin(2a)}$