You would have to know the length of the radius. The center of the circle is at one end of the radius. If you just know where some part of the radius is, and not that the part touches the circle then you cannot know where the center is without at lest a point on the circumference.
The diameter of a circle is 2 times the radius. The radius of a circle is the distance from any point on the circle to the center of the circle, and the diameter is the distance from one side of the circle to the opposite side, passing through the center.
You already know the radius.
To find the diameter you need to know what the radius of the circle which is from the center to the circumference ,the edge, then you times it by two and that's how yo find the diameter
It depends on the values you have. The base of a cylinder is a circle. If you know the circle's diameter, half it to find the radius. If you know the circle's circumference, divide by 2pi to find the radius. If you know the circle's area, divide by pi and take the square root to find the radius.
To know what a radius is you have to kno what a diameter is. The diameter is the distance accross a circle through its center. The radius is half the diameter.
Diameter = 2*Radius
Conceptually, the radius is the distance from the center of the circle to any point on its edge. If you know the circumference of the circle, then the radius is the circumference divided by 2 times pi.
just use the area formula ex... area of circle= pi(r square) if you know what your area is then plug it in then do PI / by area that will be your diameter to get the radius / your answer by 2
radius = circumference/2*pi
radius = circumference/(2*pi)