Question

Find the area of circle of a diameter is $4.2$.

Answer 1

Given

Diameter of circle $=4.2$

radius$=\frac{4.2}{2}=2.1$

Area of circle = $\pi r^2$

$=\frac{22}{7}\times (2.1{)}^2$

$=\frac{22}{7}\times 2.1\times 2.1$

$=13.86$