What is the value of cos(150°)?

Ellin asked Oct 25, 2023

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Ellin asked Oct 25, 2023

by Ellin

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27 votes

Given that cos(150°).

$\cos (150^o)=\cos (180^o-30^o)$
$\text{Use }\cos (180^o-30^o)=-\cos 30^o$

$\cos (150^o)=-\cos (30^o)$
$\text{Use }\cos (30^o)=\frac{\sqrt[]{3}}{2}\text{.}$

$\cos (150^o)=-\frac{\sqrt[]{3}}{2}$

Hence the required value is

$\cos (150^o)=-\frac{\sqrt[]{3}}{2}$

Kerryjj answered Oct 31, 2023

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