How do you solve
sin9x/1-cos^2(9x)

Using formula sin^2 x +cos^2 x = 1 you get 1 - cos^2(9x) = sin^2(9x)

so in this way this fraction will be rewrited 

sin9x/(1-cos^2(9x) = sin9x / sin^2(9x) = 1/sin9x