180 Degree Angle

180-degree angle is an angle formed when two lines or rays extend in opposing directions from a common point, producing a perfectly straight line. It is also called a straight angle.

In this article, we will learn about 180-degree angles, how to measure 180-degree angles, properties of 180-degree angles along with a few examples based on it.

What is 180 Degree Angle?

180-degree angle, also known as a straight angle, is the result of two lines or rays extending from a common point in opposing directions to produce an exact straight line.

👁 Straight-Angle-Picture

It appears as a straight line without any bends or curves. A 180-degree angle is the biggest angle that may be created in Euclidean geometry because its measure is exactly 180 degrees.

180 Degree Angle Definition

180 degree angle is defined as an angle that is created when two rays, lines, or line segments extend in opposite directions from a single endpoint, called the vertex, to produce a straight line.

The measure of a 180-degree angle is precisely 180 degrees, indicating a half-circle.

180 Degree Angle Name

180-degree angle is called a straight angle because of its ability to form a straight line. Straight angle refers to the fact that it does not bend or deviate, forming a complete half-circle or a full turn.

180 degree angle is made up of rays or lines that are aligned in opposing directions forming a straight line, hence it is called a straight angle.

Also Check, Types of Angle

How to Draw 180 Degree Angle Using Compass

Using a compass to draw a 180-degree angle is a simple procedure. Here's a detailed step by step process:

• Draw a straight line: Use your ruler to draw a straight line on the paper. Name this line as AB.

• Mark a Point: Anywhere between A and B, mark a point C.

• Draw an Arc: Taking point C as the center, draw an arc with a compass of any radius. The arc should touch line AB and extend from point the left of point C to its right, or vice versa.

• Name the Points: The straight line is cut by the arc twice. Name these points as P and Q.

• Angle formed, i.e.  PCD angle is 180 degrees.

How to Draw 180 Degree Angle Using Protractor

Steps to draw a 180 degree angle using a protractor are illustrated below:

• Draw a straight line on your paper using a ruler. Name this line as OA.

👁 Construction of straight angle step 1

• Position the protractor so that its center point aligns with one of the endpoint of the line, let it be O.

👁 Construction of straight angle step 2

• On the protractor scale, locate and mark the 180-degree reading. This mark is directly opposite the 0-degree mark. Name this point as B.

👁 Construction of straight angle step 3

• Draw a straight line using your ruler from A to the point B.

👁 Construction of Straight Angle step 4

• The angle formed, i.e. AOB is the required 180-degree angle.

Properties of 180 Degree Angle

Properties of a 180 degree angle are:

• The primary property of a 180-degree angle is its measure, which is exactly 180 degrees. This angle represents a complete half-circle or a full turn.

• The sum of the two adjacent angles formed by dividing the straight line is always 180 degrees.

• A 180-degree angle forms a perfectly straight line. It has no curvature or bend, hence, it is also known as a straight angle.

• It is also denoted by π (i.e. π = 180°)

• It can be formed by joining two right angles.

• Any angle that, when added to a 180-degree angle, results in a complete rotation (360 degrees) is its own inverse. This property is often used in trigonometry and angle transformations.

Examples of 180 Degree Angles

Some real-life examples of 180 Degree Angle found in our surrounding includes:

• 6 O’Clock: Minute hand on a clock points to the 12 at 12 o’clock and to the 6 at 6 o’clock, forming a straight line.

• Pencil: Body of a standard pencil is a straight line, extending from the eraser at the top to the tip at the bottom.

👁 Examples-of-180-Degree-Angles

Read More,

• Acute Angle
• Right Angle
• Obtuse Angle

Solved Examples on 180 Degree Angle

Example 1: If we divide a straight angle into two parts such that one of the angle measure 100°. Find the measure of other angle.

Solution:

Given:

Measure of one angle = 100°

Sum of adjacent angles of a straight line is always 180°

Therefore, Measure of another angle = 180° - 100° = 80°

So, the measure of other angle is 80°.

Example 2: If two angles are supplementary, and one of them measures 120 degrees, what is the measure of the other angle

Solution:

Supplementary angles add up to 180°.

Let one angle be x°

Given:

Measure of one angle = 120°

Measure of the other angle + 120° = 180 °

Measure of the other angle = 180° - 120°

Measure of the other angle = 60°

So, the measure of the other angle is 60°.