Помогите решить с буквой Д(дома)

Решите задачу:

$1)\quad sin \alpha =\sqrt{\frac{2}{11}}\\\\\frac{\pi}{2}\leq \alpha \leq \pi \; \; \to \; \; cos \alpha \leq 0\\\\cos \alpha =-\sqrt{1-sin^2 \alpha }=-\sqrt{1-\frac{2}{11}}=-\sqrt{\frac{9}{11}}=-\frac{3}{\sqrt{11}}\\\\\sqrt{11}cos \alpha =-\sqrt{11}\cdot \frac{3}{\sqrt{11}}=-3$

$2)\quad cos \alpha =\sqrt{\frac{1}{7}}=\frac{1}{\sqrt7}\\\\0^\circ \leq \alpha \leq 180^\circ \; \; \to \; \; sin \alpha \geq 0\\\\sin \alpha =+\sqrt{1-cos^2 \alpha }=\sqrt{1-\frac{1}{7}}=\sqrt{\frac{6}{7}}\\\\1-\sqrt{\frac{14}{3}}sin \alpha =1-\sqrt{ \frac{14}{3} }\cdot \sqrt{ \frac{6}{7} }=1-\sqrt{\frac{7\cdot 2}{1}}=1-\sqrt{14}$