Question

How do you evaluate `cos 30`?

Answer 1

`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:

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

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