The expression sin(x)cos(x)cos3(x)\displaystyle \frac{{\sin{{\left({x}\right)}}}}{{{\cos{{\left({x}\right)}}}-{{\cos}^{{3}}{\left({x}\right)}}}} simplifies to f(x)sin(x)\displaystyle \frac{{f{{\left({x}\right)}}}}{{\sin{{\left({x}\right)}}}}. Determine f(x)\displaystyle {f{{\left({x}\right)}}}.


f(x)=\displaystyle {f{{\left({x}\right)}}}=