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In this activity, we will learn about calculating the unknown angle on a straight line.

 

The angles at a point on a straight line add up to 180°

 

This diagram shows that 180° is half a complete revolution.

 

Angles on a straight line 180

 Notice that 35° + 145° = 180°

 

Let's try an example question together!

 

Example

Find the missing angle in degrees.

 

Find the missing angle on a straight line

 

Answer

The missing angle is 180° - 65° = 115°

 

Let's have a go at some questions.

10 questions