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Question: question 6 10 marks this question is based on...

Question details

Question 6 – 10 marks This question is based on your work on MU123 up to and including Unit 12. In this question, you are asked to comment on a student’s incorrect attempt at answering the question detailed below.

(a) Write out your own solution to the question, explaining your working.

(b) There are two places in the student’s attempt where a mistake has been made. Identify these mistakes and explain, as if directly to the student, why, for each mistake, their working is incorrect.

The Question

In triangle ABC, side BC has length 23 cm, and side AC has length 33 cm. D is a point on side AC such that ∠BCD = 68◦ and ∠BDA = 90◦ .

(i) Use the cosine rule to find the length of AB, giving your answer to two significant figures.

(ii) In right-angled triangle BCD, find the length of BD, giving your answer to two significant figures.

(iii) Use the sine rule in triangle ABC to find the acute angle ∠BAC, giving your answer to two significant figures.

The students incorrect attempt () using the cosine rule 232332-2 x 23 x 33 x cos 8 32.3.. The length of AB is 32 cm (to 2 s.

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