How Do I Find The Center Of A Circle And The Radius?

Finding the center depends on what tools you have available.  Here are 2 ways:

If it is a paper circle, fold it over twice and the intersect of the folds is the center.  Take a ruler and measure from this point out to the edge to find the radius.

If you have a ruler and can not fold the circle, do the following:
1. Draw a chord (a straight line from one point inside the circle to another). Don't try to go through the center.
2. Measure the chord and mark the exact center
3. Draw a line perpendicular (at a 90 degree angle) to the chord going through this center mark.
4. Repeat for a second chord (try to make this chord about 90 degrees away from the other chord)
The 2 perpendicular lines will intersect at the center of the circle.  Now you can measure out from the center to an edge to find the radius.  Hope this makes sense.

Draw about 3  lines crossing the circle and mark the point where they meet to state the centre and to to get the radius measure the diameter of the circle and divide it by 2