



 
Hi Faisal, I drew a diagram of what you described. $C$ with coordinates $(h,k)$ is the center of the circle, $b$ is the point on the circle with coordinates $(5, 16)$ and $A$ is the point where the Xaxis is tangent to the circle. I gave $A$ the coordinates $(a,b)$ but since $A$ is on the Xaxis $b = 0.$ The tangent line and the line segment $AC$ form a right angle and hence $k = 10.$ The length of $BC$ is 10units so \[(h5)^2 + (k+16)^2 = 10^{2}.\] But $k = 0.$ Solve for $h$ and write the equation of the circle. Is there another diagram for the situation you described? Penny




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