GCSE · Trigonometry (sine & cosine rules)

Area of a triangle & 3D trigonometryExam-style questions

Why ½ab sin C works for any triangle, using it in reverse to find an angle, and the method for 3D problems — find the right-angled triangle inside the solid, then work in two dimensions.

Start practising Read the lesson

14 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 3 Level 4 Level 5

1
The diagram shows a triangle with two sides of length $9.4$ cm and $12.7$ cm, and an angle of $58°$ between them.Diagram NOT accurately drawn

Work out the area of the triangle. Give your answer correct to 1 decimal place.
Level 3 · 2 marksTry it
2
A triangle has two sides of length $7.5$ cm and $9.2$ cm, and the angle between them is $41°$ .

Work out the area of the triangle. Give your answer correct to 3 significant figures.
Level 3 · 2 marksTry it