Question
The perimeter of a sector of a circle, whose radius is 20 cm, is 70
cm. If the length of a rectangle is 10 cm more than the arc subtended by the sector and its perimeter is 92 cm, then find the area (in cm2) of the rectangle.
Solution
Let the arc subtended by the sector be ‘l’ cm and the radius of the circle be ‘r’ cm According to the question, (l + 2r) = 70 Or, l = 70 – 2r = 70 – (2 × 20) = 30 cm Therefore, length of the rectangle = 30 + 10 = 40 cm Let the breadth of the rectangle be ‘b’ cm Therefore, 2 × (40 + b) = 92 Or, b = 46 – 40 = 6 cm Therefore, area of the rectangle = length × breadth = 6 × 40 = 240 cm2
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