4MA1/1FR Jan 2021, Question 10: Angles in a Triangle
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1FR (Foundation) · Calculator · 3 marks
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The question, in short
Isosceles triangle ABC has AB = AC and angle BAC = 44°. Side BC is extended to D, making BCD straight. Find x, the exterior angle ACD.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 3 marks
- 1AB = AC, so angles ABC and ACB are equal.
- 2Angle ACB = (180 − 44) ÷ 2 = 68°
- 3Angles on a straight line add to 180°: x = 180 − 68 = 112
Answer112
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