AI generatedGeometry and measuresKey Stage 3

Classifying triangles by angles

Classifying triangles by angles.

  • Use the stated properties and diagram markings, rather than judging by appearance.
  • Matching ticks mean equal lengths; matching arrows mean parallel lines.
  • A small square marks a right angle. Keep labels horizontal and include units.

Example 1

Classify the triangle by its angles.

Geometry diagramABCDiagram not to scale
Acute-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Example 2

Classify the triangle by its angles.

Geometry diagramPQRDiagram not to scale
Right-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Your turn

Question 1

Classify the triangle by its angles.

Geometry diagramABCDiagram not to scale
Check answer
Obtuse-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Question 2

Classify the triangle by its angles.

Geometry diagramPQRDiagram not to scale
Check answer
Acute-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Question 3

Classify the triangle by its angles.

Geometry diagramABCDiagram not to scale
Check answer
Right-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Question 4

Classify the triangle by its angles.

Geometry diagramPQRDiagram not to scale
Check answer
Obtuse-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.

Question 5

Classify the triangle by its angles.

Geometry diagramABCDiagram not to scale
Check answer
Acute-angled.

Check the largest angle: below 90°, exactly 90°, or above 90°.