Question

1) cosa/sin2a 2) sin2x/sinx - coax 3) cosAsin2a/tgA 4) cos2x-cos^2x

Answer 1

1. $\frac{cosa}{sin2a} =\frac{cosa}{2sinacosa} =\frac{1}{2sina}$
2. $\frac{sin2x}{sinx} -cosx = \frac{2sinxcosx}{sinx} -cosx = 2cosx-cosx=cosx$
3. $\frac{cosasin2a}{tga} =\frac{2sinacos^{2}a }{\frac{sina}{cosa} } =2cosa$
4. $cos2x-cos^{2}x =cos^{2} x-sin^{2} x-cos^{2} x=-sin^{2} x$