Interactive resource
Circle of Apollonius
Geometry. Locus of points with PA/PB = k (constant) is a circle. Free interactive GeoGebra resource — adjust parameters in the browser.
Overview
Locus of points with PA/PB = k (constant) is a circle.
Explanation
Apollonius circle: points P with PA/PB = k (k > 0, k ≠ 1) form a circle.
When k = 1 the locus degenerates to the perpendicular bisector of AB.
Useful whenever a fixed distance ratio appears.
How to use
Drag P with fixed PA/PB = k; change k to move and resize the circle.