Решите пожалуйста 1,2,3. Благодарю.

Решите задачу:

$1)\; \; cos \alpha =\frac{9}{11}\; \; ,\; \; \frac{3\pi }{2} \leq \alpha \leq 2\pi \\\\sin \alpha =-\sqrt{1-cos^2 \alpha }=\sqrt{1-\frac{81}{121}}=-\sqrt{\frac{40}{121}}=-\frac{2\sqrt{10}}{11}\\\\tg \alpha = \frac{sin \alpha }{cos \alpha } =-\frac{2\sqrt{10}}{9}\\\\2)\; sin \alpha =\frac{2}{7}\; ,\; \; \frac{\pi }{2} \leq \alpha \leq \pi \\\\cos \alpha =-\sqrt{1-sin^2 \alpha }=-\sqrt{1-\frac{4}{49}}=-\sqrt{\frac{45}{49}}=-\frac{3\sqrt{5}}{7}\\\\tg \alpha =-\frac{2}{3\sqrt5}=-\frac{2\sqrt5}{15}$

$3)\; \; tg \alpha =7\; ,\; \; 0 \leq \alpha \leq \frac{\pi }{2}\\\\cos^2 \alpha = \frac{1}{1+tg^2 \alpha } =\frac{1}{1+49}= \frac{1}{50} \\\\cos \alpha =\frac{1}{5\sqrt2}=\frac{\sqrt2}{10}\\\\sin \alpha =+\sqrt{1-cos^2 \alpha }=\sqrt{1-\frac{2}{100}}=\sqrt{\frac{98}{100}}=\frac{7\sqrt2}{10}\\\\oo$