三角学 示例

加上 ${\displaystyle 2\pi }$ 的全角，直至角度大于等于 ${\displaystyle 0}$ 且小于 ${\displaystyle 2\pi }$。

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosecant is negative in the third quadrant.

${\displaystyle \csc \left(\frac{\pi }{4}\right)}$ 的准确值为 ${\displaystyle \sqrt{2}}$。