Question : The area (in m2) of a circular path of uniform width $x$ metres surrounding a circular region of diameter d metres is _____.
Option 1: $\pi x(x+2 \mathrm{~d})$
Option 2: $\pi x(x+\mathrm{d})$
Option 3: $\pi x(2 x+\mathrm{d})$
Option 4: $\pi x\left(x+\frac{\mathrm{d}}{2}\right)$
Correct Answer: $\pi x(x+\mathrm{d})$
Solution : Radius of circular region ($r$) = $\frac{d}{2}$ Width of path = $x$ m External radius of path ($R$) = $\frac{d}{2} + x$ As we know, Area of path = $π(R^2 - r^2)$ = $\pi[(\frac{d}{2} + x)^2 - (\frac{d}{2})^2]$ = $\pi [\frac{d^2}{4} + x^2+ dx - \frac{d^2}{4}]$ = $\pi [x^2 + dx]$ = $\pi x (x + d)$ m2 Hence, the correct answer is $\pi x (x + d)$.
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Question : A 64 cm wide path is made around a circular garden having a diameter of 10 metres. The area (in m2) of the path is closest to: (Take $\pi=\frac{22}{7}$)
Option 1: 10
Option 2: 21
Option 3: 15
Option 4: 9
Question : If the sum of the diagonals of a rhombus is $L$ and the perimeter is $4P$, find the area of the rhombus.
Option 1: $\frac{1}{4}\left(\mathrm{~L}^2-\mathrm{P}^2\right)$
Option 2: $\frac{1}{4}\left(\mathrm{~L}^2-4 \mathrm{P}^2\right)$
Option 3: $\frac{1}{2}\left(\mathrm{~L}^2-4 \mathrm{P}^2\right)$
Option 4: $\frac{1}{4}\left(\mathrm{~L}^2+3 \mathrm{P}^2\right)$
Question : A circular park whose diameter is 210 m has a 5 m wide path running around it (on the outside). What is the area (in m²) of the path?
Option 1: 1020$\pi$
Option 2: 1075$\pi$
Option 3: 1050$\pi$
Option 4: 1100$\pi$
Question : If the perimeter of circle A is equal to the perimeter of semicircle B, what is the ratio of their areas?
Option 1: $\left (x+ 2\right)^{2} : 2\pi ^{2}$
Option 2: $2\pi ^{2} : \left ( x+2 \right)^{2}$
Option 3: $\left (\pi +2 \right )^{2} : 4\pi ^{2}$
Option 4: $4\pi ^{2}:\left ( \pi +2 \right)^{2}$
Question : Three circles of equal radius '$a$' cm touch each other. The area of the shaded region is:
Option 1: $\left ( \frac{\sqrt{3}+\pi}{2} \right )a^{2}$ sq. cm
Option 2: $\left ( \frac{6\sqrt{3}-\pi }{2} \right )a^{2}$ sq. cm
Option 3: $\left ( \sqrt{3}-\pi \right )a^{2}$ sq. cm
Option 4: $\left ( \frac{2\sqrt{3}- \pi}{2} \right )a^{2}$ sq. cm
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