Question

the top of an auto piston is a circle with a diameter measuring 8.4 centimeters . what is the area of the top piston ?

Answer 1

area of a circle = PI x r^2

r = 8.4/2 = 4.2

using 3.14 for PI

area = 3.14 x 4.2^2 = 55.3896 square cm

round answer as needed

Answer 2

Radius = Diameter /2

So, Radius = 8.4/2 or 4.2

4.2^2 = 17.64.

17.64 x pi = 55.39 sq cm.

cm because we are being consistent with the units of measurement already in use.