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.
Notice that 35° + 145° = 180°
Let's try an example question together!
Example
Find the missing angle in degrees.
Answer
The missing angle is 180° - 65° = 115°
Let's have a go at some questions.
View the activity introduction for more information on the topic
Read the question aloud
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Question
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Teacher explanation