A right-angled triangle has an angle of 35° and the hypotenuse is 10 cm. Find the opposite side.
Step 1 Label and identify
We have: angle = 35°, H = 10 cm
We need: O = ?
O and H → use Sin
Step 2 Write the formula
sin 35° = O10
Step 3 Rearrange for O
O = 10 × sin 35°
O = 10 × 0.5736...
O = 5.74 cm (2 d.p.)
This study notes covers Worked Example 1: Finding a Side within Trigonometry (SOH CAH TOA) for GCSE Mathematics. Revise Trigonometry (SOH CAH TOA) in Geometry & Measures for GCSE Mathematics with 19 exam-style questions and 7 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 4 of 7 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Trigonometry (SOH CAH TOA)
Which trigonometric ratio connects the opposite side and the hypotenuse in a right-angled triangle?
For the triangle shown, a student chooses to use sin to find the missing side. Explain why they chose sin rather than one of the other trigonometric ratios.