Calculate Missing Angles in Shapes

In this activity, we will learn how to identify the missing angles.

 

Remember the following rules: 

The angles in any triangle add up to a total of 180°

The angles on any straight line add up to a total of 180°

The angles around a point add up to a total of 360°

Angles in a quadrilateral add up to 360°.

 

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.