4MA1/2F Jun 2018, Question 15: Multi-Step Angle Reasoning
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2F (Foundation) · Calculator · 3 marks
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The question, in short
Use the isosceles triangle ABE with AB = AE and angle BAE = 80°, joined to rectangle BCDE, to work out the size of reflex angle x at E.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 3 marks
- 1Triangle ABE is isosceles with AB = AE, so angles ABE and AEB are equal
- 2(180 − 80) ÷ 2 = 50, so angle AEB = 50°
- 3BCDE is a rectangle, so angle BED = 90°
- 4The angles at E go all the way round: x = 360 − 50 − 90
- 5x = 220
Answer220
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