How to explain calculating angles in quadrilaterals in angles in quadrilaterals to your child
27 October 2026
Understanding angles in quadrilaterals is a key skill for the 11+ maths exam. When your child knows three of the angles in a four-sided shape, they can always find the fourth. This simple example shows how to approach these questions step by step.
Worked example
A quadrilateral has three angles: 75°, 85°, and 140°. Find the missing angle.
Step 1: Add the three known angles: 75 + 85 + 140 = 300°
Step 2: Subtract this from 360°: 360 - 300 = 60°
The missing angle is 60°.
Key insight: After working through an example, your child will spot that the angles in any quadrilateral always add up to 360°. They are now ready to practise similar questions and build confidence with angles in quadrilaterals.
