Trigonometry Trammel

A large yellow, black, white and orange rectangular exhibit with an informatin panel on the right and a circular orange disc with numbers on the left.
A large yellow, black, white and orange rectangular exhibit with an informatin panel on the right and a circular orange disc with numbers on the left.

The trigonometry functions ‘sine’ and ‘cosine’ describe angles in terms of the lengths of sides of triangles.

How it works

Turn the handle and pointers labelled ‘sin’ and ‘cos’ will automatically work out these trigonometric functions, including angles as the ratio of lengths of triangles’ legs.

Things to try or ask around the exhibit

  • The pointers point to numbers which are the sine (sin) and cosine (cos) of that angle (θ). Choose an angle and note its sine value. How much further do you need to turn the handle in order to get the same value for cosine?
  • Can you find the angles where the sine and cosine of the angle are the same? (sinθ = cosθ)
  • Can you find the angles where the sine of the angle is half of the cosine? (2 × sinθ = cosθ)

Background

Sine, cosine are functions that describe the angles using the ratios of sides of right angle triangles. This is useful when using triangles in manufacturing, navigation, making furniture or constructing buildings.