Question : If $\frac{1}{x^{2}}+x^{2}$ represents the radius of circle $P$ and $\frac{1}{x}+x=17$, which of the following best approximates the circumference of circle $P$?
Option 1: $287\pi$
Option 2: $547\pi$
Option 3: $574\pi$
Option 4: $278\pi$
Correct Answer: $574\pi$
Solution : Given: $\frac{1}{x}+x=17$ Squaring both sides, we have, ⇒ $(\frac{1}{x}+x)^{2}=17^{2}$ ⇒ $\frac{1}{x^{2}}+x^{2}+2=289$ ⇒ $\frac{1}{x^{2}}+x^{2}=287$ Circumference of circle $P$ = $2\pi r$ = $2×\pi ×287$ = $574\pi $ Hence, the correct answer is $574\pi $.
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Question : The radius of a circle is 1.75 cm. What is the circumference of the circle? (Take $\pi=\frac{22}{7}$)
Option 1: 5.5 cm
Option 2: 11 cm
Option 3: 9.63 cm
Option 4: 22 cm
Question : Three equal circles of unit radius touch one another. Then the area of the circle circumscribing the three circles is:
Option 1: $6 \pi (2+ \sqrt3)^2$
Option 2: $\frac{\pi}{6} (2+ \sqrt3)^2$
Option 3: $\frac{\pi}{3} (2+ \sqrt3)^2$
Option 4: $3\pi (2+ \sqrt3)^2$
Question : If $x^2 = y+z$, $y^2=z+x$, $z^2=x+y$, then the value of $\frac{1}{x+1}+\frac{1}{y+1}+\frac{1}{z+1}$ is:
Option 1: –1
Option 2: 1
Option 3: 2
Option 4: 4
Question : What is the value of $\frac{x^2-x-6}{x^2+x-12}÷\frac{x^2+5x+6}{x^2+7x+12}$?
Option 1: $1$
Option 2: $\frac{(x-3)}{(x+3)}$
Option 3: $\frac{(x+4)}{(x-3)}$
Option 4: $\frac{(x-3)}{(x+4)}$
Question : Two identical circles each of radius $2\;\mathrm{cm}$ intersect each other such that the circumference of each one passes through the centre of the other. What is the area (in $\mathrm{cm^2}$) of the intersecting region?
Option 1: $\frac{8\pi }{3}-2\sqrt{3}$
Option 2: $\frac{8\pi }{3}-\sqrt{3}$
Option 3: $\frac{4\pi }{3}-\sqrt{3}$
Option 4: $\frac{4\pi }{3}-2\sqrt{3}$
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