4. Формулы приведения (записать в тетрадь). 1. Опорная точка π/2 (n = 1): sin(π/2 − α) = cos α; sin(π/2 + α) = cos α; cos(π/2 − α) = sin α; cos(π/2 + α) = −sin α; tg(π/2 − α) = ctg α; tg(π/2 + α) = −ctg α; ctg(π/2 − α) = tg α; ctg(π/2 + α) = −tg α. 2. Опорная точка π (n = 2): sin(π − α) = sin α; sin(π + α) = −sin α; cos(π − α) = −cos α; cos(π + α) = −cos α; tg(π − α) = −tg α; tg(π + α) = tg α; ctg(π − α) = −ctg α; ctg(π + α) = ctg α. 3. Опорная точка 3π/2 (n = 3): sin(3π/2 − α) = −cos α; sin(3π/2 + α) = −cos α; cos(3π/2 − α) = −sin α; cos(3π/2 + α) = sin α; tg(3π/2 − α) = ctg α; tg(3π/2 + α) = −ctg α; ctg(3π/2 − α) = tg α; ctg(3π/2 + α) = −tg α. 4. Опорная точка 2π (n = 4): sin(2π − α) = −sin α; sin(2π + α) = sin α; cos(2π − α) = cos α; cos(2π + α) = cos α; tg(2π − α) = −tg α; tg(2π + α) = tg α; ctg(2π − α) = −ctg α; ctg(2π + α) = ctg α.

Формулы приведения:

1. Опорная точка \(\frac{\pi}{2}\) (\(n=1\))

• \(\sin\left(\frac{\pi}{2}-\alpha\right)=\cos\alpha\)
• \(\sin\left(\frac{\pi}{2}+\alpha\right)=\cos\alpha\)
• \(\cos\left(\frac{\pi}{2}-\alpha\right)=\sin\alpha\)
• \(\cos\left(\frac{\pi}{2}+\alpha\right)=-\sin\alpha\)
• \(\operatorname{tg}\left(\frac{\pi}{2}-\alpha\right)=\operatorname{ctg}\alpha\)
• \(\operatorname{tg}\left(\frac{\pi}{2}+\alpha\right)=-\operatorname{ctg}\alpha\)
• \(\operatorname{ctg}\left(\frac{\pi}{2}-\alpha\right)=\operatorname{tg}\alpha\)
• \(\operatorname{ctg}\left(\frac{\pi}{2}+\alpha\right)=-\operatorname{tg}\alpha\)

2. Опорная точка \(\pi\) (\(n=2\))

• \(\sin(\pi-\alpha)=\sin\alpha\)
• \(\sin(\pi+\alpha)=-\sin\alpha\)
• \(\cos(\pi-\alpha)=-\cos\alpha\)
• \(\cos(\pi+\alpha)=-\cos\alpha\)
• \(\operatorname{tg}(\pi-\alpha)=-\operatorname{tg}\alpha\)
• \(\operatorname{tg}(\pi+\alpha)=\operatorname{tg}\alpha\)
• \(\operatorname{ctg}(\pi-\alpha)=-\operatorname{ctg}\alpha\)
• \(\operatorname{ctg}(\pi+\alpha)=\operatorname{ctg}\alpha\)

3. Опорная точка \(\frac{3\pi}{2}\) (\(n=3\))

• \(\sin\left(\frac{3\pi}{2}-\alpha\right)=-\cos\alpha\)
• \(\sin\left(\frac{3\pi}{2}+\alpha\right)=-\cos\alpha\)
• \(\cos\left(\frac{3\pi}{2}-\alpha\right)=-\sin\alpha\)
• \(\cos\left(\frac{3\pi}{2}+\alpha\right)=\sin\alpha\)
• \(\operatorname{tg}\left(\frac{3\pi}{2}-\alpha\right)=\operatorname{ctg}\alpha\)
• \(\operatorname{tg}\left(\frac{3\pi}{2}+\alpha\right)=-\operatorname{ctg}\alpha\)
• \(\operatorname{ctg}\left(\frac{3\pi}{2}-\alpha\right)=\operatorname{tg}\alpha\)
• \(\operatorname{ctg}\left(\frac{3\pi}{2}+\alpha\right)=-\operatorname{tg}\alpha\)

4. Опорная точка \(2\pi\) (\(n=4\))

• \(\sin(2\pi-\alpha)=-\sin\alpha\)
• \(\sin(2\pi+\alpha)=\sin\alpha\)
• \(\cos(2\pi-\alpha)=\cos\alpha\)
• \(\cos(2\pi+\alpha)=\cos\alpha\)
• \(\operatorname{tg}(2\pi-\alpha)=-\operatorname{tg}\alpha\)
• \(\operatorname{tg}(2\pi+\alpha)=\operatorname{tg}\alpha\)
• \(\operatorname{ctg}(2\pi-\alpha)=-\operatorname{ctg}\alpha\)
• \(\operatorname{ctg}(2\pi+\alpha)=\operatorname{ctg}\alpha\)