Question

Помогите решить с буквой Д(дома)

Answer 1

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

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