2. Упростите выражение tg² t (-1 + 1/sin² t).

\( \tan^2(t) left(-1 + \frac{1}{\sin^2(t)}\right) = \tan^2(t) left(\frac{1 - \sin^2(t)}{\sin^2(t)}\right) = \tan^2(t) \frac{\cos^2(t)}{\sin^2(t)} = \frac{\sin^2(t)}{\cos^2(t)} \frac{\cos^2(t)}{\sin^2(t)} = 1 \)