Kuala Lumpur Trial 2025 Add Maths Paper 2, Question 5Circular Measure
Solved on video in English · Form 5, Circular Measure · 7:17 video
The question
Diagram 4 shows two circles of radius 3 cm and 4 cm with centres A and B respectively, whose centres are 5 cm apart. The two circles intersect at C and D. The lines AC and BC are tangents to the circles centred at B and A respectively. [Use π = 3.142]
(a) Calculate the angle CAB, in radians.
Diagram 4 shows two circles of radius 3 cm (centre A) and 4 cm (centre B), centres 5 cm apart, intersecting at C and D, with AC and BC as tangents. [Use π = 3.142]
(b) Calculate the perimeter, in cm, of the whole diagram.
142]
(c) Calculate the area, in cm², of the whole diagram.
7:17Part (a)
Step 1
In triangle ACB the sides are AC = 3 cm, BC = 4 cm and AB = 5 cm.
3 more steps, each with the reason for it, in the full solution
Final answer
∠CAB = 0.9274 rad
Where students lose marks
Watch out: in the cosine rule, BC (opposite ∠CAB) is the side squared on its own. Give the answer in radians, not 53.13°.
Part (b)
5 more steps, each with the reason for it, in the full solution
Final answer
Perimeter = 33.27 cm
Where students lose marks
Watch out: the outer arc is the major arc, so use 2π − 2∠CAB, not 2∠CAB. Remember 2π = 6.284 here.
Part (c)
4 more steps, each with the reason for it, in the full solution
Final answer
Area = 71.91 cm²
Where students lose marks
Watch out: add the two major sectors AND both triangles ACB and ADB (12 cm² in total). Don't skip a triangle.
Watch every step of this question solved on video (7:17), with the reason behind each step and a box that checks your own answer.
No card. Every past-year question on video, in English and BM.
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