‘How to use sin, cos and tan to find the size of an angle in right angle triangles’
.. can seem a little daunting.. but they are used extensively in maths and have some real, practical applications.
Watch the video and try the quick test.
Click here to try the Quick Test SohCahToa
You can use sin, cos and tan – some of the “trigonometric functions”
- to find the size of an angle in a right angle triangle or
- to find the length of a side in a right angle triangle (more about this in the next post)
To find the size of an angle you need to know the lengths of two of the sides.
For a right angle triangle the sides are labelled relative to the angle you need to find – in other words, ‘opposite’ is opposite. So:
A typical exam question would be something like:
“Calculate the size of angle x in this right angle triangle. Give your answer correct to 3 significant figures’
With these type of questions it’s better to have a series of steps:
- label the hypotenuse first (longest side)
- label the side adjacent to the angle you want to work out
- label the side opposite to the angle
- use SohCahToa – in this question we are going to use Toa
- make sure the calculator is in degree mode (look for D symbol on your display)
- Use the inverse trigonometric function and brackets for the ratio
Trigonometry is an really useful part of maths and is used in architecture, building and all sorts of construction. From finding the heights of trees, towers or ocean tides to navigation, physics and astronomy – you’ll find some trigonometry.
Did you know that the ‘trig’ bit means ‘triangle’ and the ‘metry’ bit means ‘measure?!’
Watch the videos on YouTube: