cot^3/csct=cost(csc^2t-1)
\(\dfrac{\cot^3t}{\csc t}=\dfrac{\dfrac{\cos^3t}{\sin^3t}}{\dfrac1{\sin t}}=\dfrac{\cos^3t}{\sin^2t}=\cos t\cot^2t=\cos t(\csc^2t-1)\)
