Geometry and measuresKey Stage 3

Exterior angles of a polygon add to 360°

Use polygon angle facts to find missing values.

  • An exterior angle lies between one side and the extension of its neighbouring side.
  • One exterior angle at each vertex of a convex polygon adds to . This works for regular and irregular polygons.

Example 1

Find the sum of the marked exterior angles.

One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.

Example 2

Find the sum of the marked exterior angles.

One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.

Your turn

Question 1

Find the sum of the marked exterior angles.

Check answer
One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.
Question 2

Find the sum of the marked exterior angles.

Check answer
One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.
Question 3

Find the sum of the marked exterior angles.

Check answer
One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.
Question 4

Find the sum of the marked exterior angles.

Check answer
One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.
Question 5

Find the sum of the marked exterior angles.

Check answer
One exterior angle at every vertex makes one complete turn.
One exterior angle at every vertex makes one complete turn.
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