The area of a circle is 15400 $$cm^{2}$$. What is the positive difference between the radius and the circumference of the circle? [Use $$\pi = \frac{22}{7}$$]

Solution

The area of a circle is 15400 $$cm^{2}$$.

area of a circle = $$\pi\ \times\ \left(radius\right)^2$$

$$15400=\frac{22}{7}\times\ \left(radius\right)^2$$
$$700=\frac{1}{7}\times\ \left(radius\right)^2$$
$$70^2=\ \left(radius\right)^2$$
radius of a circle = 70 cm
Positive difference between the radius and the circumference of the circle = $$2\times\ \pi\ \times\ radius\ -radius\ $$
= $$2\times\ \frac{22}{7}\times70\ -70$$
= $$44\times10\ -70$$
= 440-70
= 370 cm