Trigonometry in Right-Angled Triangles

We talked in class about using ‘SOHCAHTOA’ to calculate angles and sides in right-angled triangles. If you have difficulty remembering SOHCAHTOA then consider using a mnemonic. 

We also talked about trigonometry questions that involve angles of elevation and depression.  These questions are normally best answered by sketching a diagram. In the diagram you should see a right-angled triangle and therefore use trigonometry.  If you find these questions difficult then have a look at the lesson on MyMaths (Shape>Trigonometry>Trig Angles of Elevation) - the new password is prime.  There is also a lesson on MyMaths about bearings (Shape>Angles>Bearings) but this lesson just helps you understand how bearings work and does not involve trigonometry.

Here’s our worksheet from the lesson, including answers. 

So far we’ve only looked at right-angled triangles.  Next we’ll look at the Sine Rule and Cosine Rule, which we can use for determining angles and sides in all types of triangle.