# How do you find the value of cos (pi)/6?

##### 1 Answer

Jul 18, 2016

sqrt3/2

#### Explanation:

There are 2 ways, that don't need calculator

a. Trig table of special arc -->

b. Use triangle trigonometry

Consider a right triangle ABH that is half of an equilateral triangle

ABC

Angle

Leg

We have

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Edit from r3ce:

I believe another option to also look at especially for precalculus if it's applicable is the unit circle. It's basically a picture of certain common values for sine and cosine for angles such as