AI generatedGeometry and measuresKS3 / GCSE

Constructing a triangle from two sides and an angle

Constructing a triangle from two sides and an angle.

  • Use a sharp pencil, ruler and compasses or protractor as specified.
  • Keep the arcs and guide marks that show how the construction was made.
  • Check the required lengths and angles without erasing the construction.

Example 1

Construct triangle ABC with AB = 4 cm, AC = 3 cm and angle BAC = 40°. Keep your construction marks.

See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 4 cm. At A construct 40°. Measure AC = 3 cm along that ray, then join B to C.

Example 2

Construct triangle ABC with AB = 5 cm, AC = 3 cm and angle BAC = 45°. Keep your construction marks.

See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 5 cm. At A construct 45°. Measure AC = 3 cm along that ray, then join B to C.

Your turn

Question 1

Construct triangle ABC with AB = 6 cm, AC = 3 cm and angle BAC = 50°. Keep your construction marks.

Check answer
See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 6 cm. At A construct 50°. Measure AC = 3 cm along that ray, then join B to C.

Question 2

Construct triangle ABC with AB = 7 cm, AC = 3 cm and angle BAC = 55°. Keep your construction marks.

Check answer
See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 7 cm. At A construct 55°. Measure AC = 3 cm along that ray, then join B to C.

Question 3

Construct triangle ABC with AB = 8 cm, AC = 3 cm and angle BAC = 60°. Keep your construction marks.

Check answer
See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 8 cm. At A construct 60°. Measure AC = 3 cm along that ray, then join B to C.

Question 4

Construct triangle ABC with AB = 9 cm, AC = 3 cm and angle BAC = 65°. Keep your construction marks.

Check answer
See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 9 cm. At A construct 65°. Measure AC = 3 cm along that ray, then join B to C.

Question 5

Construct triangle ABC with AB = 10 cm, AC = 3 cm and angle BAC = 70°. Keep your construction marks.

Check answer
See the completed construction.
Constructed triangleABCDiagram not to scale

Draw AB = 10 cm. At A construct 70°. Measure AC = 3 cm along that ray, then join B to C.