In this activity, we will learn how to identify the missing angle in a triangle.
Remember: The angles in any triangle add up to a total of 180°
Let's try an example question together.
Example
Here is a scalene triangle.
All of its angles and sides are different.
What is the size of the angle marked with a question mark?
Answer
Here, we have been given two of the angles: 54° and 64°
To find the missing angle we need to add these two angles and subtract the total from 180.
54 + 64 = 118
180 - 118 = 62
The missing angle is 62°
We can check this is correct by doing: 54 + 64 + 62 = 180
Let's have a go at some questions now.
View the activity introduction for more information on the topic
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Question
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Teacher explanation