Question

If the area of a circle is $A$, radius of the circle is $r$ and circumference of it is $C$, then

• A. $rC=2A$
• B. $\frac{C}{A}=\frac{r}{2}$
• C. $AC=\frac{r^2}{4}$
• D. $\frac{A}{r}=C$

Answer 1

The correct option is A $rC=2A$

Area of circle with radius ${}^{\prime }{r}^{\prime }=A=\pi r^2$

$\Rightarrow \pi r=\frac{A}{r}$ ...(1)

Circumference $C=2\pi r$

$\Rightarrow \pi r=\frac{C}{2}$ ....(2)

Equating eq(1) & eq(2), we get

$\frac{A}{r}=\frac{C}{2}$

$\Rightarrow 2A=Cr$