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Year 10 - Maths

Applying trigonometric ratios in 3D

Right-angled trigonometry

Unit Summary

In this unit, pupils are introduced to a variety of situations where trigonometric ratios are required, such as 3-D problems and problems of elevation or depression.

Lesson Summary

You will learn to apply knowledge of trigonometric ratios to 3D problems.

Key Notes

  • If angles are involved, then you may wish to apply trigonometric ratios to the 3D problem
  • This allows you to calculate the angle between the line and the plane
  • It can also be used to find missing lengths if the angle is known

Vocabulary To Learn

  • Hypotenuse: The hypotenuse is the side of a right-angled triangle which is opposite the right angle.
  • Trigonometric ratios: The trigonometric ratios are ratios between each pair of lengths in a right-angled triangle.
  • Cross-section: A cross-section is a 2D face made from cutting straight through any plane of a 3D object.

Common Mistakes To Avoid

  • Trigonometric ratios cannot be applied to 3D shapes.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

If angles are involved, then you may wish to apply trigonometric ratios to the 3D problem. This allows you to calculate the angle between the line and the plane.

2. Use this key word in a maths sentence and explain it clearly. 'Hypotenuse'

The hypotenuse is the side of a right-angled triangle which is opposite the right angle. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Trigonometric ratios cannot be applied to 3D shapes. Correction: Pupils may benefit from imaging the cuboid is 'sliced' through and a triangle drawn on the now visible face.

More Lessons In This Unit

Browse all guides in the Year 10 Maths guide library.