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. $cos2x-cos^{2}x =cos^{2} x-sin^{2} x-cos^{2} x=-sin^{2} x$