\(\textbf{1)}\) \( \csc ^2 {x} (1-\cos ^2 {x}) = 1 \)
\(\,\,\,\,\,\,\csc ^2 {x} (1-\cos ^2 {x}) = 1\)
\(\,\,\,\,\,\,\csc ^2 {x} (\sin ^2 {x}) = 1\)
\(\,\,\,\,\,\,\frac{1}{\sin^2{x}} (\sin ^2 {x}) = 1\)
\(\,\,\,\,\,\,\frac{\sin^2{x}}{\sin^2{x}}= 1\)
\(\,\,\,\,\,\,1 = 1\)