Year 6
Use shape properties and angle facts to compare, classify and solve missing-angle problems.
Geometry - properties of shape
Shapes can be classified by sides, angles and symmetry. Unknown angles can often be found by using known totals in triangles, quadrilaterals and regular polygons.
Classify by properties
A square has equal sides and four right angles, while a rectangle has four right angles but only opposite sides equal.
| Shape | Key properties |
|---|---|
| square | equal sides, 4 right angles |
| rectangle | opposite sides equal, 4 right angles |
The properties tell you the shape family.
Use angle totals
Angles in a triangle total 180 degrees.
Known totals help find missing angles.
A triangle has angles 70°, 60° and one missing angle. What is the missing angle?
| Known angles | Total |
|---|---|
| 70° and 60° | 180° |
Identify the shape first, then choose the property or angle fact that applies.
Which shape has equal sides and four right angles?
| Shape | Property |
|---|---|
| square | equal sides, 4 right angles |
Angles in a triangle total:
A triangle has angles 70°, 60° and ? The missing angle is:
A quadrilateral has interior angles totalling:
Which property helps classify a rectangle?
Watch for these when working through the lesson.
These ideas fit closely with this lesson.