666. Используя формулы приведения, вычислить: 1) tg (5π/4); 2) sin (7π/6); 3) cos (5π/3); 4) ctg (5π/3); 5) sin (−13π/6); 6) cos (−7π/3); 7) tg (−2π/3); 8) ctg (−7π/4).

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Вопрос:

Accepted Answer

\(\operatorname{tg}\frac{5\pi}{4}=\operatorname{tg}\frac{\pi}{4}=1\).
\(\sin\frac{7\pi}{6}=-\sin\frac{\pi}{6}=-\frac12\).
\(\cos\frac{5\pi}{3}=\cos\frac{\pi}{3}=\frac12\).
\(\operatorname{ctg}\frac{5\pi}{3}=-\operatorname{ctg}\frac{\pi}{3}=-\frac{\sqrt3}{3}\).
\(\sin\left(-\frac{13\pi}{6}\right)=\sin\left(-\frac{\pi}{6}\right)=-\frac12\).
\(\cos\left(-\frac{7\pi}{3}\right)=\cos\left(-\frac{\pi}{3}\right)=\frac12\).
\(\operatorname{tg}\left(-\frac{2\pi}{3}\right)=\operatorname{tg}\frac{\pi}{3}=\sqrt3\).
\(\operatorname{ctg}\left(-\frac{7\pi}{4}\right)=\operatorname{ctg}\frac{\pi}{4}=1\).

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