College Physics Problem 1.22

What is the area of a circle 3.102 cm in diameter?


The area of a circle can be computed using the formula below when radius is given.

\displaystyle A=\pi r^2

We also know that the radius is half the diameter, so the area can be calculated using the formula,

\displaystyle A=\pi \left(\frac{d}{2}\right)^2

So, by direct substitution

\displaystyle A=\pi \left(\frac{3.102\:cm}{2}\right)^2=7.557\:cm^2          ☚

The area of the circle is 7.557 square centimetre.