Prior to looking at different types of angles and their names, we need to have a good understanding of degree measure and how we use it to measure angle sizes.
At more basic level Math, degrees are the most common method of measuring the size of angles.
With an angle being a specific amount of rotation.
How to Write Degrees,
Degrees in a Circle
The symbol for degrees is a small circle above the right side of a number.
So 45 degrees looks like 45°.
A full rotation all the way around a full circle is of size 360°.
A quarter of the way around a circle is of size 90°.
Half way around a circle is 180°, and three quarters of a way around a circle is of size 270°.
Angles of size 40 degrees and 130 degrees inside a circle would look like the following.
As will be viewed later on in the page. Different sized angles have different names to classify them.
It’s also the case that angles don’t only go up to 360° in size.
We can keep going beyond one full rotation of a circle as far as we would like.
The picture below gives a basic example of where an angle of size 410° is shown.
Degree Measure Examples
What size is the blue angle in each of the following cases.
1.1
1.2
1.3
Names and Types of Angles
Different types of angles have different names to identify and classify them.
Below is a selection of some of the most common angle types that can be encountered in Math.
Right Angle
A right angle is an angle that is exactly 90° in size.Usually right angles are presented as a square.
Acute Angle
An acute angle is an angle that is less than 90° in size.
Obtuse Angle
An obtuse angle is an angle that is larger than 90°, but smaller than 180°.
Straight Angle
A straight angle is an angle that is exactly 180°.Which is the angle on a straight line.
Reflex Angle
A reflex angle is an angle where the size is greater than 180°, but less than 360° in size.
Adjacent Angles
Adjacent angles happen to be angles that share a common point/vertex, and also a common side, while not overlapping each other.
Angle Positive and Negative Direction
Depending on how the size of an angle is measured, the angle can be classed as being in a positive direction or a negative direction.
Congruent Angles
Congruent angles in Math are simply angles that are of the same size. Though they can look different depending on how they are drawn.The two angles pictured below are congruent. They are the same size, but just presented slightly differently.
Types of Angles, Summary
