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Question 1
The diagram shows three circles, each of radius 4 cm. The centres of the circles are A, B and C such that ABC is a straight line and AB = BC = 4 cm. Work out the t... show full transcript
Step 1
Answer
To find the area of one shaded segment in circle A, we first need to determine the angle of the sector formed at center A. Since AB = BC = 4 cm and the radius of the circles is also 4 cm, triangle ABC is isosceles with sides AB and AC equal. The angle at A can be found using the cosine rule or recognizing symmetry.
The angle at A is 120 degrees (as angle B is formed by the two radii).
The area of the sector of circle A can be calculated as:
Next, we find the area of triangle ABC:
For triangle ABC, the height can be calculated by using trigonometry, which gives the height as:
Thus, the area of triangle ABC is:
Therefore, the area of the shaded segment in circle A is:
Step 2
Answer
Using the same approach for circle C, we again have an angle of 120 degrees at center C.
Thus, the area of the sector in circle C is equal to that of circle A:
And the area of triangle ABC remains unchanged:
The area of the shaded segment in circle C is also:
Step 3
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