Solve cos(π/4)

Problem

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

Step-by-step solution

$\frac{\pi}{4}$ radians $= 45°$ .
On the unit circle at $45°$ , x-coordinate is $\frac{\sqrt{2}}{2}$ .
Cosine equals the x-coordinate: $\cos\bigl(\tfrac{\pi}{4}\bigr) = \frac{\sqrt{2}}{2}$ .

Answer

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

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