## Related Words

# Alternate Interior Angles

## Definition of Alternate Interior Angles

When two lines are cut by a transversal, the pair of angles formed interior of the two lines and on the opposite of the transversal is called Alternate Interior Angles.

### More About Alternate Interior Angles:

If two parallel lines are cut by a transversal, the alternate interior angles are congruent

### Examples of Alternate Interior Angles

In the figure shown,** l** is the transversal that cut the pair of lines. Angles

*and*

**a***and angles*

**d***and*

**b***are alternate interior angles.*

**c**

### Video Examples: Alternate Interior Angles

### Solved Example on Alternate Interior Angles

**Ques: **Find the measure of angle *m *in the figure shown.

##### Choices:

- A. 120
^{o} - B. 180
^{o} - C. 60
^{o} - D. Insufficient information

Correct Answer: C

#### Solution:

- Step 1: 120
^{o}+ n = 180^{o}[Straight angle.] - Step 2:
*n = 60*^{o}[Solve for n.] - Step 3:
*n = 60*^{o}implies m = 60^{o}, because m and n are alternate interior angles and so they are congruent.

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