Instructions

In each of these questions, two quianitties A and B are given: Compare the two quantities and mark answer as

Question 157

Two circles with the same radius are blocked inside a rectangle.

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A: The area of the shaded region.
B: The area of one and a half circles.

Solution

The length of the rectangle is equal to the diameter of two circles or $$4r$$

Similarly, the breadth is equal to the diameter of 1 circle i.e. $$2r$$.

We know the area of rectangle is $$lb=\left(4r\right)\left(2r\right)=8r^2$$

The area of 1 circle is $$\pi r^2$$

Area of both circles combined is $$2\pi r^2$$

So, area of shaded region is $$A=8r^2-2\pi r^2\approx\ 8r^2-6.28r^2=1.72r^2$$

And the area of one and half circle is $$B=\dfrac{3}{2}\pi r^2\approx4.71r^2$$

Hence, B > A.

So, the answer is Option B


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