Topics
9. Shapes and angles
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United States of AmericaUT
Grade 4

9.07 Angles on a straight line

Lesson
Practice
Lesson

Are you ready?

Do you remember how many degrees are in a full turn? Let's try this problem to review. 

How many $1^\circ$1° angles fit into a full circle?

Learn

A straight line is half of a full turn, so it has a measure of $180$180 degrees.
This also means that angles on a straight line will add up to $180$180 degrees.

Let's learn more about angles on a straight line.

Apply

Find the size of the missing angle.

  1. $=$= $\editable{}$$^\circ$°

Remember!

Angles on a straight line always add up to $180$180 degrees.

Outcomes

4.MD.7

Recognize angle measure as additive. When an angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the angle measures of the parts. Solve addition and subtraction problems to find unknown angles on a diagram in real world and mathematical problems, for example by using an equation with a symbol for the unknown angle measure.

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