Question

Determine which of the following pairs of angles are coterminal.

$330°,-60°$

Answer 1

STEP 1 : Determining whether the angles are coterminal or not

Coterminal angles are angles in standard position (angles with the initial side on the positive $x$-axis) that have a common terminal side. For example, the angles $30°,–330°$ and $390°$ are all coterminal as shown in figure.

To find a positive and a negative angle coterminal with a given angle, you can add and subtract $360°\times n$$(nispositiveinteger)$ if the angle is measured in degrees or $2\pi \times n$ $(nispositiveinteger)$ if the angle is measured in radians.

$330°,-60°$

Adding $360°$ to $-60°$ we get,

$-60°+360°=300°$

Hence, we can say that $330°,-60°$ are not coterminal angles.