Arctangent definition

The arctangent function is the inverse function of y = tan(x).

arctan(y) = tan^-1(y) = x+ kπ

For every

k = {…,-2,-1,0,1,2,…}

For example, If the tangent of 45° is 1:

tan(45°) = 1

Then the arctangent of 1 is 45°:

arctan(1) = tan^-1(1) = 45°

Arctangent table

Arctan on calculator

In order to calculate arctan(y) on a calculator:

1. Press shift+tan buttons.
2. Enter the angle.
3. Press the = button.