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.