Question

Find the area of a circle with diameter 10 cm . Use the value 3.14 for π , and do not round your answer. Be sure to include the correct unit in your answer.

Answer 1

Formula for the area of a circle:

A = πr²                   [A = area        r = radius]

The radius is $\frac{1}{2}$ (half) the diameter. Since the diameter = 10cm, the radius = 5cm.

You know:

r = 5cm         Substitute/plug this into the equation

A = πr²

A = π(5)²    

A = 25π  ->     A = 25(3.14)

A = 78.5cm²