Interior angles of a polygon | Maths | Quizalize & Oak National Academy

Starter quiz

An ______ angle is an angle formed inside a polygon by two of its edges.

acute

alternate

exterior

interior ✓

obtuse
The interior angles of a triangle sum to ______°.

'180' ✓
What is the size of ∠ABC?

73°

84° ✓

95°

108°
What is the value of $x$ ? $x=$ ______.

'49' ✓
Starting with the smallest, sort the angles in ascending order of size.

1

⇔

acute

2

⇔

right angle

3

⇔

obtuse

4

⇔

reflex
What is the size of the angle $x$ °?

52° ✓

58°

64°

A pentadecagon has 15 sides. The minimum number of triangles that it could be split into is ______.

'13' ✓
An octadecagon has 18 sides. Which calculation would find the sum of its interior angles?

$16 \times 180$ ✓

$18 \times 180$

$20 \times 180$
The interior angles in the hexagon sum to ______°.

'720' ✓
The interior angles of a pentagon sum to ______°.

'540' ✓
The size of the angle $x$ ° is ______°.

'141' ✓
The size of the angle $x$ ° is ______°.

'112' ✓

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Any polygon can be split into triangles.
Using these triangles you can demonstrate the rule for the interior angle sum of a polygon.
A missing interior angle in any polygon can be found.

When splitting a polygon into triangles, pupils may draw line segments that cross inside the shape.

By choosing a single common vertex for all the triangles, the line segments will not cross inside the shape.

Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.
Interior angle - An interior angle is an angle formed inside a polygon by two of its edges.
Sum - The sum is the total when numbers are added together.