4024/21 Oct/Nov 2025, Question 5: Angles in a Triangle
Cambridge O Level Mathematics 4024 · Paper 21 (Calculator) · Calculator · 3 marks
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The question, in short
Isosceles triangle with top angle 56°; find the base angle x and the reflex angle y at the bottom left vertex.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Part (a) · 2 marks
Use the equal sloping sides and the 56° top angle to calculate the base angle x.
- 1Base angles are equal (isosceles triangle)
- 2x = (180 − 56) ÷ 2 = 62
Answer62
Part (b) · 1 mark
Use the value of x to find the reflex angle y outside the triangle at that vertex.
- 1Base angles are equal: x = (180 − 56) ÷ 2 = 62
- 2Angles at a point add to 360°: y = 360 − 62 = 298
Answer298
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Also searched as: 4024/21/O/N/25 · 4024_w25_qp_21 · 4024 w25 21 · question 5.
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