Trigonometry

Senior High 5 questions

What trigonometry means

You use the ratios of opposite, adjacent and hypotenuse to find missing sides or angles in right-angled triangles. This helps you solve geometry questions and supports later work on exam-style problems.

What you will practise

Identify opposite, adjacent and hypotenuse sides correctly
Choose sine, cosine or tangent for each question
Work out missing side lengths from given measurements
Find simple angle values from trigonometric ratios
Check answers using a calculator in degree mode

Before you start

You should already be able to recognise parts of a right-angled triangle and measure angles in degrees. Basic calculator use is also important.

Not confident yet? Work through Quadratic equations first.

Worked example

One question from this skill's own question bank, shown with its full working.

Question

In a right-angled triangle, sine of an angle equals:

adjacent over hypotenuse
opposite over hypotenuse
opposite over adjacent
hypotenuse over opposite

Answer: opposite over hypotenuse

Working: SOH: Sine equals Opposite divided by Hypotenuse.

Common mistakes to avoid

Mixing up opposite and adjacent sides. Label the triangle from the chosen angle before using a ratio.
Using the wrong trigonometric ratio. Match sine, cosine or tangent to the sides needed.
Forgetting the triangle must be right-angled. Check for the 90 degree angle first.
Leaving the calculator in radian mode. Set it to degrees for school triangle questions.

Curriculum and exam alignment

Ghana GES SHS syllabusWASSCE

This topic normally appears in SHS mathematics work on triangle ratios and right-angled triangle problems. It is also useful for WASSCE preparation, where clear use of sine, cosine and tangent often appears in structured questions.

Curriculum notes are a general guide to where this work normally sits. Always check the syllabus your school or examination body is currently using.