Question

How would you find the exact trigonometric ratio for an angle whose radian measure is `(4pi)/3`?

Answer 1

An angle of `(4pi)/3` is in Quadrant 3 with a reference angle of `pi/3`
`sin((4pi)/3) = -sqrt(3)/2`
`cos((4pi)/3) = -1/2`
`tan((4pi)/3) = sqrt(3)`

Explanation:

See diagram below:

Note that `pi/3` is one of the standard trigonometric angles.