Interior Angles Of A Triangle
In these lesson, we will learn
- about interior angles of triangles
- the properties of the interior angles of a triangle
- how the properties can be used to find the missing angles inside a triangle
- how the sum of interior angles of a triangle can be used to set up equations.
Related Pages
Exterior Angles Of A Triangle
Types Of Triangles
Angles In A Triangle
The following diagram shows that the sum of angles in a triangle is 180°. Scroll down the page for more examples and solutions on how to find missing angles in a triangle.
Interior Angles
The interior angles of a triangle are the angles inside the triangle.
Properties of Interior Angles
- The sum of the three interior angles in a triangle is always 180°.
- Since the interior angles add up to 180°, every angle must be less than 180°.
Find missing angles inside a triangle
Example:
Find the value of x in the following triangle.
Solution:
x + 24° + 32° = 180° (sum of angles is 180°)
x + 56° = 180°
x = 180° – 56° = 124°
How to find the missing angle inside a triangle.
Example:
Find the missing angle in a triangle.
A = 15°, B = ?, C = 92°
Using Interior Angles Of Triangle To Set Up Equations
How to use the sum of the interior angles of a triangle to solve problems?
Example:
- Write an equation and solve for the unknown.
- Substitute your answer into each expression to determine the measure of the angles.
- Give reasons for your answers.
Using the sum of the interior angles of a triangle, write an equation and solve for the unknown.
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