0580/11 Oct/Nov 2025, Question 15: Angles in a Triangle
Cambridge IGCSE Mathematics 0580 · Paper 11 (Core) · Non-calculator · 3 marks
اقرأ هذا الحل مشروحاً بالعربي ←
The question, in short
Using the straight line ABC with angle DBC = 140° and triangle ABD having AD = BD, calculate the size of angle x at D.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 3 marks
- 1Angle ABD = 180 − 140 = 40° (angles on a straight line)
- 2AD = BD, so angle BAD = angle ABD = 40°
- 3x = 180 − 2 × 40 = 100
Answer100
Stuck on a step? Read the free lesson: Angles in a Triangle
Practise more angles in a triangle questions
Real 0580 past-paper questions, marked on your working like the exam, with a worked solution for every part.
Practise free on LemmaraMore past-paper questions on angles in a triangle
Also searched as: 0580/11/O/N/25 · 0580_w25_qp_11 · 0580 w25 11 · question 15.
Lemmara is an independent study tool, not affiliated with or endorsed by Cambridge International Education. The worked solutions are Lemmara’s own.