The radius of a circle is the distance from the center to any point on the circumference. The diameter is the distance from one side of the circle's circumference, through the center of the circle, to the opposite side.
Let's recall the definitions of radius and diameter.
Radius: Distance from the center of the circle to any point on the circumference.
Diameter: Distance from one side of the circle's circumference, through the center of the circle, to the opposite side.
We have been given that EN=13 ft, which is a radius the circle. According to the definitions, the diameter is twice the radius. Therefore, the diameter is 13* 2=26 ft.
