Question 33
The area of a circle got increased by 22 cm when the radius was increased by 1 cm. What was the original radius?
Solution
area of circle = $$\pi\times r^2$$
radius = r
ATQ
$$\pi(r + 1)^2- \pi\times r^2 = 22$$
$$\pi((r + 1)^2- r^2) = 22$$
$$\frac{1+ 2r}{7}=1$$
2r = 6
r = 3cm
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