# Find missing angles when two or more polygons are joined

# Find missing angles when two or more polygons are joined

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## Lesson details

### Key learning points

- In this lesson, we will apply regular polygon knowledge to find missing angles when two or more polygons are joined together.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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### 4 Questions

Q1.

The sum of interior angles of a polygon is 720º. How many sides does the polygon have?

5

7

8

Q2.

The sum of interior angles of a polygon is 2880º. How many sides does the polygon have?

15

16

17

Q3.

The sum of interior angles of a regular polygon is 3960º. What is the size of each interior angle of the regular polygon?

150º

170º

175º

Q4.

The sum of interior angles of a regular polygon is 5040º. What is the size of each exterior angle of the regular polygon?

100.8º

168º

79.2º

### 4 Questions

Q1.

The diagram shows two hexagons joined. Calculate the size of the angle marked b.

144º

60º

90º

Q2.

A regular pentagon and a regular hexagon are joined. Calculate the size of angle a.

105º

117º

144º

Q3.

An octagon and a nonagon are joined. Calculate the size of the angle labelled g.

105º

117º

75º

Q4.

Calculate the size of the angle marked.

15º

18º

27º