The student's incorrect attempt We first calculate the angle at A, using the fact that all three anGles in a triangle add up to 180. We have A = 180 - (90 +23) = 67, and so the anGle at A is 670. Using the Sine Rule in triangle ABC, we have C sin A sinc' SO a= sing X sinA 76.6 sin 460 X sin670 = 98.02.. . So the length of BC is 98 am ( to the nearest cm). The length of BH is the same as the length of At, and triangle A-HC is right andled, so we have COs 23'S _adj _CH hyp 98 ' So 98 CH= COs 230 = 106.46... Therefore to the nearest cm, the perpendicular height of the triangle is 106cm. (a) Look at the student's answer for the length CH. Using what you know about right-angled triangles, and without performing any further calculations, explain how you know that this calculated length must be wrong. (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. (c) Do you think that the student's approach to solving the problem is the most efficient method? Give a reason for your answer. (d) Write out your own solution to the problem, explaining your working