Home > Resources > Homework > Math > Unit Circle

$ ext{How to Find the Reference Angle Not on Unit Circle}$

Answer 1

Abigail Nelson

Thomas Walker

To find the reference angle of an angle not on the unit circle, follow these steps:

1. Determine the quadrant in which the angle is located.

2. Use the following rules based on the quadrant to find the reference angle:

For an angle $\theta$ in the first quadrant, the reference angle is $\theta$.

For an angle $\theta$ in the second quadrant, the reference angle is $180^\circ – \theta$.

For an angle $\theta$ in the third quadrant, the reference angle is $\theta – 180^\circ$.

For an angle $\theta$ in the fourth quadrant, the reference angle is $360^\circ – \theta$.

Example: Find the reference angle for $210^\circ$.

Since $210^\circ$ is in the third quadrant, we use the rule for the third quadrant:

$\text{Reference Angle} = 210^\circ – 180^\circ = 30^\circ$

Therefore, the reference angle for $210^\circ$ is $30^\circ$.

Answer 2

Alex Thompson

Alex Thompson

To find the reference angle of an angle not on the unit circle, follow these steps:

1. Identify the quadrant of the angle.

2. Use the appropriate formula based on the quadrant:

In the first quadrant: $ heta$

In the second quadrant: $180^circ – heta$

In the third quadrant: $ heta – 180^circ$

In the fourth quadrant: $360^circ – heta$

Example: Find the reference angle for $300^circ$.

$300^circ$ is in the fourth quadrant, so:

$ ext{Reference Angle} = 360^circ – 300^circ = 60^circ$

The reference angle for $300^circ$ is $60^circ$.

Answer 3

Amelia Mitchell

William King

To find the reference angle:

1. Determine the quadrant.

2. Use the quadrant-specific rule:

1st quadrant: $ heta$

2nd quadrant: $180^circ – heta$

3rd quadrant: $ heta – 180^circ$

4th quadrant: $360^circ – heta$

Example: For $135^circ$ in the second quadrant:

$ ext{Reference Angle} = 180^circ – 135^circ = 45^circ$

Thus, the reference angle is $45^circ$.