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ABC is a right-angled triangle - Edexcel - GCSE Maths - Question 9 - 2019 - Paper 3
Question 9
ABC is a right-angled triangle. Here is Sarah’s method to find the length of BC. $BC^2 = AB^2 + AC^2$ $= 6^2 + 8^2$ $= 100$ $BC = 10$ (a) What mistake has Sarah ... show full transcript
Worked Solution & Example Answer:ABC is a right-angled triangle - Edexcel - GCSE Maths - Question 9 - 2019 - Paper 3
Step 1
What mistake has Sarah made in her method?
Answer
Sarah made a mistake in her application of the Pythagorean theorem. The correct formula should be:
However, she should be using the appropriate values, where she adds the squares of the lengths of the two legs of the triangle. The calculation was incorrectly simplified:
The calculation should yield:
Instead, she has also added incorrectly and did not clearly express that she was indeed using the right triangle analysis.
Step 2
Explain why Roy's diagram is not correct.
Answer
Roy's diagram is incorrect because he has not used the correct scale factor. The scale factor of means that each side of triangle PQR should be halved to produce the corresponding sides of triangle XYZ. Additionally, Roy may have mistakenly located point C, which should remain the center of the enlargement, yet he may have altered its position, leading to incorrect relative placement of the vertices.