 # Angles in shapes for AQA GCSE Maths 1. Sum of angles in a triangle
2. Sum of angles in a square
3. Sum of angles and inner angles
4. Sum of angles and outer angles

The sum of interior angles in a triangle is 180°. If the side of a triangle is extended, an angle is created outside the triangle called an exterior angle. A square has 4 interior angles, all of equal size 90°. The sum of interior angles in a polygon can be found by dividing the polygon into a number of triangles. The exterior angles of a polygon can be found by extending the sides of the polygon to form an angle outside the shape. # 1

Calculate the sum of interior angles in a pentagon.

540° # 2

Calculate the size of the exterior angles in the shape shown and hence, calculate the size of the interior angles.

exterior angle = 72°
interior angle = 108° # 3

If x is the number of sides in a polygon, write a formula that can be used to find the sum of interior angles in the polygon.

180º(x − 2) # 4

Find the size of angle x.

38° # 5

Calculate the sum of the interior angles in the shape shown.

1080° End of page