Odpowiedź:
[tex]\text{a)}\hspace{4pt}\dfrac{1}{\sin^2\alpha}[/tex]
Szczegółowe wyjaśnienie:
[tex]\vspace{4pt}1+\dfrac{1}{\text{tg}^2\alpha}=1+\dfrac{1}{\left(\dfrac{\sin\alpha}{\cos\alpha}\right)^2}=1+\dfrac{\cos^2\alpha}{\sin^2\alpha}=\dfrac{\sin^2\alpha}{\sin^2\alpha}+\dfrac{\cos^2\alpha}{\sin^2\alpha}=\\=\dfrac{\sin^2\alpha+\cos^2\alpha}{\sin^2\alpha}=\dfrac{1}{\sin^2\alpha}[/tex]
