← Back to the activity

Class 10 Maths — Introduction to trigonometry

Find sine, cosine and tangent in a right-angled triangle and recall the standard angles.

Name: ________________________

Before you start

One angle of this right-angled triangle has been marked. Find out what that angle and each of the three sides are called.

1234
  1. 1. Opposite
  2. 2. Adjacent
  3. 3. Hypotenuse
  4. 4. The marked angle

Mark the other corner instead and opposite and adjacent swap over. The hypotenuse never moves, because it is fixed by the right angle rather than by the angle you chose.

  1. 1.What is tan 30°?

    • a) √3/2
    • b) 1/2
    • c) √3
    • d) 1/√3

  2. 2.For any angle θ, what does sin²θ + cos²θ come to?

  3. 3.In a right-angled triangle the side opposite an angle is 3 cm and the side next to it is 4 cm. What is the tangent of that angle? Give your answer as a fraction.

  4. 4.What is sin 60°?

    • a) 1/2
    • b) 1/√3
    • c) √3/2
    • d) √3

  5. 5.Match each trigonometric ratio to its value.

    • sin 30°
    • cos 30°
    • tan 45°
    • sin 0°
    • tan 60°
    • 1
    • √3
    • 0
    • √3/2
    • 1/2

  6. 6.What is cos 0°?

  7. 7.What is sin 90°?

  8. 8.What is sin 30°? Give your answer as a fraction.

Answer key — Class 10 Maths — Introduction to trigonometry

  1. 1. d) 1/√3
  2. 2. 1
  3. 3. 3/4
  4. 4. c) √3/2
  5. 5. sin 30° → 1/2; cos 30° → √3/2; tan 45° → 1; sin 0° → 0; tan 60° → √3
  6. 6. 1
  7. 7. 1
  8. 8. 1/2