Remember that
The area of a circle is equal to
[tex]A=\pi\cdot r^2[/tex]we have
A=78.5 unit2
I will assume pi=3.14
substitute in the formula
[tex]\begin{gathered} 78.5=3.14\cdot r^2 \\ r^2=\frac{78.5}{3.14} \\ r=5\text{ units} \end{gathered}[/tex]the diameter is two times the radius
so
D=2(5)=10 units
therefore
