180 Degree Angle - Shape, Examples - Cuemath

180 Degree Angle

The 180-degree angle is a straight angle as it forms a straight line. It is exactly half of the full angle (360-degree angle). If we talk about a real-life example of a 180-degree angle, then a perfect example is the angle between the two hands of a clock at 6 o'clock. The angle between the two hands of the clock is 180° because it forms a straight line.

1.	What is 180 Degree Angle?
2.	180 Degree Angle Name
3.	How to Draw 180 Degree Angle?
4.	FAQs on 180 Degree Angle

What is 180 Degree Angle?

A 180-degree angle is a straight angle and it is exactly half of a revolution. It is also called a half-circle angle. A straight angle is produced by a straight line. The two arms of the angle which are making 180-degree are just opposite to each other from the common vertex. A 180-degree angle modifies the direction of a point. A 90-degree angle is half of the 180-degree angle and it is known as a right angle. Look at the image given below shows how a 180-degree angle looks.

In the above image, rays AO and OB share a common point O. AO and OB rays are opposite to each other. AB is a straight line and forms an angle of 180 degrees.

180 Degree Angle Name

An angle that measures 180 degrees is called a straight angle. Whenever we construct a 180-degree angle, it always forms a straight line, that is why it is known as a straight angle. There are different names for angles of different measurements. For example, half of a 180-degree angle, i.e a 90-degree angle is known as a right angle in geometry. Similarly, double of 180 degrees, that is 360-degree angle is known as a complete angle. Angles that are less than 180 degrees are categorized as acute and obtuse angles.

Two angles that together form 180 degrees are known as supplementary angles. While two or more angles combining together at a point on a line forming 180 degrees are known as linear pairs of angles.

How to Draw 180 Degree Angle?

The 180-degree angle can be drawn with the help of a protractor and compass.

Constructing 180-Degree Angle Using a Protractor

Follow the given steps to construct a 180-degree angle with the help of a protractor:

• Step 1: Draw a ray OA.
• Step 2: Place the protractor at point O.
• Step 3: In the inner circle of the protractor, look for 180° reading and with a pencil mark a dot and name it C.
• Step 4: Join O and C. Now, ∠AOC=180 degree angle.

Constructing 180-Degree Angle With a Compass

Follow the given steps to construct a 180-degree angle with the help of a compass.

• Step 1: Draw a straight line with help of a ruler and name it AB.
• Step 2: Mark a point O anywhere between A and B.
• Step 3: Take O as a center point, draw an arc of any radius with help of a compass, the arc should be from the left of point O to the right of O, or vice-versa, touching the line AB.
• Step 4: The arc cuts the straight line at two points. Mark the cuts as points C and D.
• Step 5: Thus, the angle COD is 180 degrees angle.

Important Notes

• The 180-degree angle is also called a straight angle, half-circle, or semi-circle.
• A 180-degree angle can be constructed with a protractor or a compass.

Related Articles

Check these interesting articles related to the 180-degree angles in geometry.

• 30 Degree Angle
• 60 Degree Angle
• Measuring Angles
• 30-60-90 Triangle