Margie Marx

2021-12-17

What is $\mathrm{cos}135$?

xandir307dc

Expert

$135=\frac{3\pi }{4}$
Thus,
$\mathrm{cos}\frac{3\pi }{4}=\mathrm{cos}\left(\pi -\frac{\pi }{4}\right)$
$=-\mathrm{cos}\left(\frac{\pi }{4}\right)$
$=-\frac{1}{\sqrt{2}}$

Paineow

Expert

The value of $\mathrm{cos}135$ is $-\frac{1}{\sqrt{2}}$.

RizerMix

Expert

$\mathrm{cos}135°=\mathrm{sin}\left(90°-135°\right)$
$=\mathrm{sin}\left(-45°\right)$
$=-\mathrm{sin}45°$
$=-\frac{\sqrt{2}}{2}$

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