Solve cos(π/4) = √2/2

Problem

$\cos\bigl(\tfrac{\pi}{4}\bigr)$

Step-by-step solution

$\frac{\pi}{4}$ 弧度 $= 45°$ 。
在單位圓上 $45°$ 處，x 座標為 $\frac{\sqrt{2}}{2}$ 。
餘弦等於 x 座標： $\cos\bigl(\tfrac{\pi}{4}\bigr) = \frac{\sqrt{2}}{2}$ 。

Answer

$\cos\bigl(\tfrac{\pi}{4}\bigr) = \tfrac{\sqrt{2}}{2}$

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