Question

The point (5,4) lies on a circle. what is the length of the radius of this circle if the center is located at (3,2)

Answer 1

Use the x and y values from your point and the h and k from the center to write the equation you need to solve for r.  The general form of the equation for a circle is $(x-h) ^{2} +(y-k) ^{2} = r^{2}$.  We will fill in accordingly: $(5-3) ^{2}+(4-2) ^{2} = r^{2}$.  Solve for r to get that $r= \sqrt{8}$