高校数学
三角関数 基本定理 \begin{aligned} \sin(-\theta)&=-\sin\theta \\ \cos(-\theta)&=\cos\theta \\ \tan(-\theta)&=-\tan\theta \\ \sin^2\theta+\cos^2\theta&=1 \end{aligned} 余弦定理 \begin{aligned} a^2=b^2+c^2-2bc\cos\theta \end{aligned} 加法定理 \begin{aligned} \sin(\alpha+\beta)&=\sin\alpha\cos\beta+\cos\alpha\sin\beta \\ \sin(\alpha-\beta)&=\sin\alpha\cos\beta-\cos\alpha\sin\beta \\ \cos(\alpha+\beta)&=\cos\alpha\cos\beta-\sin\alpha\sin\beta \\ \cos(\alpha-\beta)&=\cos\alpha\cos\beta+\sin\alpha\sin\beta \\ \tan(\alpha+\beta)&=\frac{\tan\alpha+\tan\beta}{1-\tan\alpha\tan\beta} \\ \tan(\alpha-\beta)&=\frac{\tan\alpha-\tan\beta}{1+\tan\alpha\tan\beta} \end{aligned} 2倍角の公式 \begin{aligned} \sin2\alpha&=\sin(\alpha+\alpha) \\ &=2\sin\alpha\cos\alpha \\ \cos2\alpha&=\cos(\alpha+\alpha) \\ &=\cos^2\alpha-\sin^2\alpha=2\cos^2\alpha-1=1-2\sin^2\alpha \end{aligned} 半角の公式 \begin{aligned} \sin^2\frac\alpha2&=\frac{1-\cos\alpha}2 \\ \cos^2\frac\alpha2&=\frac{1+\cos\alpha}2 \\ \tan^2\frac\alpha2&=\frac{\sin^2\frac\alpha2}{\cos^2\frac\alpha2}=\frac{1-\cos\alpha}{1+\cos\alpha} \end{aligned} 半角...