Question

sinx-sin3x/sin^2x-cos^2x=2sinx

Answer 1

For reference :
      $sin \hspace{1 mm}A-sin \hspace{1 mm}B=2cos( \frac{A+B}{2} )sin( \frac{A-B}{2} ) \\ \\ cos \hspace{1 mm}2x=cos^{2} \hspace{1 mm}x - sin^{2} \hspace{1 mm}x$