D Equals 9.8 mi

Find the Area to the nearest 10th with pi being 3.14

A = (Pi) r^2

A is area

(Pi) is 3.14

r is radius of the circle to the second power (or squared)

Since the problem gives you diameter, you must divide that number in half to get the radius. 9.8/2=4.9

The radius is 4.9mi.

Now set up the problem.

A = (3.14) (4.9^2)

Using order of operations, solve each set of parentheses.

A = (3.14) (24.01)

Now multiply the two numbers.

A=75.3914square miles

Round to the nearest 10th.

A=75.39 square miles

Assuming D is the diameter you are finding the area of a circle so the formula is A = (3.14) r

R=d/2=4.9

A = (3.14) 4.9

A=15.4