You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
Trigonometry uses the ratios of sides in right-angled triangles to find unknown sides and angles. For Edexcel GCSE Mathematics, all students need SOHCAHTOA. Higher tier students also need exact trigonometric values, the sine rule, cosine rule and the area formula using sine.
| Term | Meaning |
|---|---|
| Opposite | The side opposite the angle you are working with |
| Adjacent | The side next to the angle you are working with (not the hypotenuse) |
| Hypotenuse | The longest side, opposite the right angle |
| SOHCAHTOA | A mnemonic: Sin = Opp/Hyp, Cos = Adj/Hyp, Tan = Opp/Adj |
For a right-angled triangle with angle theta:
| Ratio | Formula | When to use |
|---|---|---|
| sin theta | Opposite / Hypotenuse | You know or want Opp and Hyp |
| cos theta | Adjacent / Hypotenuse | You know or want Adj and Hyp |
| tan theta | Opposite / Adjacent | You know or want Opp and Adj |
Edexcel Formula Sheet: SOHCAHTOA is NOT on the formula sheet — memorise it.
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.