# Trigonometry : Coterminal Angles

## Example Questions

### Example Question #1 : Coterminal Angles

Find the least positive coterminal angle to .

Explanation:

To find a coterminal angle, you must add or subtract . The question is asking for the least positive coterminal angle, so you must add  until you reach a positive angle.

The angle is still negative, so you must continue.

The angle is still negative, so you must continue.

The angle is still negative, so you must continue.

### Example Question #492 : Trigonometry

What is the coterminal angle of 82o?

-8o

-90o

-45o

-278o

-98o

-278o

Explanation:

The coterminal angle is the negative angle that travels from from the original angle.

### Example Question #3 : Coterminal Angles

Find a positive and a negative angle coterminal with a  angle.

Explanation:

Coterminal angles are angles in standard position that have a common terminal side. In order to find a positive and a negative angle coterminal with , we can add and subtract . So we can write:

So a  angle and a  angle are coterminal with a  angle.

### Example Question #1 : Coterminal Angles

Find a positive and a negative angle coterminal with a  angle.

Explanation:

Coterminal angles are angles in standard position that have a common terminal side. In order to find a positive and a negative angle coterminal with , we need to subtract one full rotation () and two full rotations ():

So a  angle and a  angle are coterminal with a  angle.

### Example Question #1 : Coterminal Angles

Identify coterminal angles among the following pairs:

Explanation:

Coterminal angles are angles in standard position that have a common terminal side.

So of the given pairs only is the correct pair.

In order to examine the given pairs we can add to an angle or subtract from an angle:

### Example Question #1 : Coterminal Angles

Which of the following angles is coterminal to ?

Explanation:

Coterminal angles share a common side when both are in standard position.

Thus, to find a coterminal angle for , add  to it to get a coterminal angle of .

### Example Question #1 : Coterminal Angles

Determine the next nearest positive and nearest negative coterminal angle to

Explanation:

In order to find a coterminal angle we must either subtract or add multiples of . To find the nearest positive coterminal angle we add :

To determine the nearest negative coterminal angle we subtract :

### Example Question #1 : Coterminal Angles

Determine the nearest negative coterminal angle to

Explanation:

In order to determine a coterminal angle we add or subtract a multiple of . In this case since the angle is positive and we want the nearest negative coterminal angle, we subtract  until we obtain the first negative angle as follows:

### Example Question #1 : Coterminal Angles

Find the least positive coterminal angle to

Explanation:

To determine a coterminal angle we must add  to the original angle. In order to find the smallest positive coterminal angle, we add until we obtain the first positive angle. We first need to find the least common denominator as follows:

### Example Question #501 : Trigonometry

Find a positive and negative angle that are coterminal with a angle.