Question

Find the diameter of a circle if the area is 153.86m². Use 3.14 for pi.

Answer 1

The formula for the area of a circle is $A = \pi r^2$. Lets set this equal to the area given to find the radius. 
$153.86 = \pi r^2$
$49 = r^2$
$7 = r$
The diameter is twice the radius, meaning the answer is 7*2 = 14.

Answer 2

6.998 i think it is right idk though