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:
![example of a right angle](https://user-images.githubusercontent.com/17547686/31929587-4f167f38-b8a5-11e7-8ee7-e76fc239e866.png)
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:
![example of a straight angle](https://user-images.githubusercontent.com/17547686/31929586-4efbd912-b8a5-11e7-8f43-5d73cca6e2eb.png)
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:
![screen shot 2017-10-24 at 10 22 45](https://user-images.githubusercontent.com/17547686/31929585-4ee08266-b8a5-11e7-8af6-9860a8c46e67.png)
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:
![example of an obtuse angle](https://user-images.githubusercontent.com/17547686/31929584-4ec4b216-b8a5-11e7-943d-ea74ce460f1b.png)
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.