Worked example
27 October 2026
Triangles are one of the most important shapes your child will meet in the 11+ maths.com uk preparation. Understanding their properties helps with many geometry questions. Here, we focus on how to find a missing angle when two angles are known.
Worked example
Find the missing angle in a triangle where two angles are 50° and 60°.
Step 1: Remember that all the angles in a triangle add up to 180°.
Step 2: Add the two angles you know. 50° + 60° = 110°.
Step 3: Subtract this from 180°. 180° - 110° = 70°.
The missing angle is 70°.
After working through this example, your child will spot that the angles in any triangle always add up to 180°. This skill means they can confidently solve similar triangle angle questions in their practice.
