User:Min666645



$$\cos^{2}\theta + \sin^{2}\theta =1$$

$$\cos^{2}\theta - \sin^{2}\theta =\cos2\theta $$

$$a \sin x+b \cos x= \sqrt{a^2+b^2} \sin (x+  \sin^{-1}  \frac{b}{\sqrt{a^2+b^2}} )$$

ko:사용자:Min666645