## Real Trigonometry

Updated June 2017

# Trigonometry: use in finding heights

These excellent materials were designed at Leeds Metropolitan University and are excellent for seeing trigonometry in real use.

- Teacher/pupil task sheet with Clinometer template for angle measuring.
- Theodolite poster – how to use to find a height.
- File showing how to use theodolite: 15 pages includes answers.
- Another theodolite example to find height of a wall.
- The related YouTube channel (here) has 5 videos including one that shows how to make the clinometer (here).
- Instructions and template for making a trig-wheel.
- For interactives related to this click the Interactives tab just above – will not work on iPads and iPhones.

# Trigonometry: ship’s course

Another example of a real use of trigonometry (to find a ship’s course) comes from Maths at Work, on the NCETM site (found here): includes video.

# Trigonometry: height of tower at British Museum

The British Museum has a KS3 challenge to find the height of a tower in its great court (February 2016). BM KS3 Maths Challenge (includes other ideas as well).

## Interactives

**If you use Chrome as your browser**then these interactive files might not work (you are instead asked if you want to Keep or Discard the files), then Discard and

**go to the link here**and follow the instructions to enable the relevant plugin. Mac and Windows instructions are both there: scroll down.

**You only have to do this once.**You will need relevant permission to do this on the computer.

## Practical lesson

- Create clinometers or borrow theodolites. Borrow long tapes from PE, use metre rules or laser distance measures.
- Go outside and have pupils stand different distances away from eg the school building (if you can).
- Measure distance from school building, use clinometer to find angle, take distance of height of clinometer above ground level.
- Have each pupil calculate height of building and then use mean, mode or median to decide ‘height’.
- Consider rounding, accuracy, think about which errors of measurement have the biggest impact.
- Think about other ways to find the height of the building – could any of these be more accurate?
- Find true height of building from building plans!
- With brick buildings finding the height of e.g. 10 layers of bricks is usually the most accurate method.