Trigonometry GCSE revision and worksheets

What you need to know:

There are three trigonometric functions that can help us learn things about right-angles which you have to know. If \theta is an acute angle in a right-angled triangle and “opposite, adjacent, hypotenuse” are the relative three sides of the triangle, then the functions are:

• \sin \theta = \dfrac{opposite}{hypotenuse}
• \cos \theta = \dfrac{adjacent}{hypotenuse}
• \tan \theta = \dfrac{opposite}{adjacent}

These are most commonly remembered with the acronym SOHCAHTOA. It’s important to make sure that you understand the labels of adjacent, opposite, and hypotenuse, and how they depend on which angle in the triangle you’re dealing with. You may be asked to use these to find both angles and side-lengths, so you should be familiar with doing both.