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How do you evaluate $cos 30$ ?

1 Answer

Jan 10, 2017

$cos(30^@)=sqrt(3)/2$

Explanation:

Consider an equilateral triangle (with interior angles of $60^@$ ) and sides of length $2$ which has been bisected as in the image below:
enter image source here

By definition $cos="adjacent side"/"hypotenuse"$

So in this case
$color(white)("XXX")cos(30^@)=sqrt(3)/2$

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