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Celeste International School

Grade 5 · Worksheet

Angles

Angles in a triangle

Name: ______________________________Date: ______________Score: ______ / 20
  1. 1.

    Two angles of a triangle are 30° and 70°. What is the third angle?

    °
  2. 2.

    Two angles of a triangle are 40° and 55°. What is the third angle?

    °
  3. 3.

    Two angles of a triangle are 35° and 45°. What is the third angle?

    °
  4. 4.

    Two angles of a triangle are 100° and 40°. What is the third angle?

    °
  5. 5.

    A right-angled triangle has a right angle (90°) and an angle of 45°. What is the third angle?

    °
  6. 6.

    The angles inside a triangle always add up to 180°.

    True False
  7. 7.

    An isosceles triangle has two equal base angles of 50° each. What is the top (apex) angle?

    °
  8. 8.

    An isosceles triangle has a top angle of 100°. The two base angles are equal. What is each base angle?

    °
  9. 9.

    The angles in an equilateral triangle are all 80°.

    True False
  10. 10.

    A right-angled triangle has a right angle and an angle of 55°. What is the third angle?

    °
  11. 11.

    Which rule helps you find the third angle of a triangle when you know two angles?

    1. AAngles in a triangle add up to 180°
    2. BAngles in a triangle add up to 360°
    3. CThere are 90° in a right angle
    4. DAngles on a straight line add up to 90°
  12. 12.

    A triangle has angles 90°, 45° and 45°. What type of triangle is it?

    1. ARight-angled isosceles
    2. BEquilateral
    3. CScalene
    4. DObtuse-angled
  13. 13.

    A triangle has angles of 35°, 45° and 100°. Put its angles in order, from smallest to largest.

    Write the order (smallest to largest) in the boxes:

    • ?100°
    • ?35°
    • ?45°
  14. 14.

    A triangle has sides 8 cm, 8 cm and 8 cm. What type is it?

    1. AEquilateral
    2. BIsosceles
    3. CScalene
  15. 15.

    A triangle has sides 4 cm, 4 cm and 4 cm. What type is it?

    1. AEquilateral
    2. BIsosceles
    3. CScalene
  16. 16.

    A triangle has sides 6 cm, 6 cm and 10 cm. What type is it?

    1. AEquilateral
    2. BIsosceles
    3. CScalene
  17. 17.

    How many degrees is a quarter turn?

    °
  18. 18.

    How many degrees is a full turn?

    °
  19. 19.

    What type of angle is 58°?

    1. AAcute
    2. BRight angle
    3. CObtuse
  20. 20.

    What type of angle is 103°?

    1. AAcute
    2. BRight angle
    3. CObtuse
Celeste International School

Answer key

Angles — Angles in a triangle

  1. 1.80 °
  2. 2.85 °
  3. 3.100 °
  4. 4.40 °
  5. 5.45 °
  6. 6.True
  7. 7.80 °
  8. 8.40 °
  9. 9.False
  10. 10.35 °
  11. 11.A. Angles in a triangle add up to 180°
  12. 12.A. Right-angled isosceles
  13. 13.35°, 45°, 100°
  14. 14.A. Equilateral
  15. 15.A. Equilateral
  16. 16.B. Isosceles
  17. 17.90 °
  18. 18.360 °
  19. 19.A. Acute
  20. 20.C. Obtuse