4MA1/1F Jan 2021, Question 9: Multi-Step Angle Reasoning
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1F (Foundation) · Calculator · 4 marks
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The question, in short
Quadrilateral ABCD with angles DAB = 59°, ABC = 115°, BCD = 68°; isosceles triangle ADE has AE = AD and EDC straight. Find x, angle AED, justifying each step.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 4 marks
- 1Angle ADC = 360° − (59° + 115° + 68°) = 118° (angles in a quadrilateral add to 360°)
- 2Angle ADE = 180° − 118° = 62° (angles on a straight line add to 180°)
- 3AE = AD, so angle AED = angle ADE (base angles of an isosceles triangle)
- 4x = 62
Answer62
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