Find the missing angle in a triangle

In these lessons we look into finding the measure of an angle in a triangle.

The following diagrams show some triangles with missing interior and exterior angles. Scroll down the page for step by step solutions on how to find the missing angles in triangles.

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Finding the Missing Angles of a Triangle
How to find the missing interior and exterior angles of a triangle?

We can use the property that the angles of a triangle add up to 180 degrees.
Step 1: Find the given angles
Step 2: Subtract the given angles from 180 to get the missing angle.

Angles of Triangles Add Up To 180 Degrees
Ex: Could a triangle have the given angle measures?
a) 115, 35, 30
b) 45, 45, 60

Angles of Triangles Add Up To 180 Degrees
Since all three angles add up to 180 degrees, you can find the missing angle by subtraction.

Angles of Triangles Add Up To 180 Degrees
Find two missing angles that are equal.

How to Find the Missing Angle in a Triangle?

How to find a missing angle in a triangle?

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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