## Angles: Acute, Obtuse, Straight and Right

There are four types of angles depending on their size in degrees. These are:

• Right angles
• Straight angles
• Acute angles
• Obtuse angles

### Right angles

Right angles are angles that have a measure of exactly 90°. For example, the angle at the corner of a square or rectangle is a right angle. An example of a right angle is below:

### Straight angles

Right angles are angles that have a measure of exactly 180°. For example, a straight line has a straight angle. An example of a straight angle is below:

### Acute angles

Acute angles are angles that have a measure of less than 90°. For example, a capital letter "A" has an acute angle. An example of an acute angle is below:

### Obtuse angles

Obtuse angles are angles that have a measure of more than 90° but less than 180°. For example, a clock showing 5 o'clock has an obtuse angle. An example of an obtuse angle is below:

## Examples

#### Example 1

What is the measure of the largest integer acute angle? Since acute angles are angles with a measure less than 90°, the largest integer acute angle will have a measure of 89°.

#### Example 2

What is the measure of the smallest integer obtuse angle? Since obtuse angles are angles with a measure larger than 90°, the smallest integer obtuse angle will have a measure of 91°.

#### Example 3

What is the measure of the angle in a capital letter "L", and what type of angle is it?The measure of the angle in a capital letter "L" is 90°, and the angle is a right angle.