Edexcel IGCSE Math A Foundation 4.8.B right-triangle trigonometry

Edexcel IGCSE Math A syllabusMath A 4MA1First assessment 2018

Practise right-triangle trigonometry by labelling opposite, adjacent and hypotenuse sides, then choosing sin, cos or tan.

How this is tested

Choose sine, cosine or tangent after labelling sides relative to the angle.
Calculate a missing length or angle and round to the requested accuracy.
Combine trigonometry with circle or multi-step diagram information when required.

28 A B C is a right-angled triangle.

Diagram NOT accurately drawn

$A C=21 \mathrm{~cm} \quad B C=15 \mathrm{~cm} \quad$ angle $A B C=90^{\circ}$
The point D lies on AB such that $D B=9 \mathrm{~cm}$
Work out the size of angle ACD
Give your answer correct to one decimal place.

How this is tested

Question 28