How do you prove (csc(t)-1)(csc(t)+1)=cot^2(t)?

$\left(\frac{1}{\sin} x - 1\right) \left(\frac{1}{\sin} x + 1\right) = \left(\frac{1}{\sin} ^ 2 x - 1\right) = \frac{1 - {\sin}^{2} x}{\sin} ^ 2 x$=
$= {\cos}^{2} \frac{x}{\sin} ^ 2 x = {\cot}^{2} x$