When a point moves in a plane according to some given conditions the path along which it moves is called a locus. Locus Theorem Locus Theorem 1: The locus of points at a fixed distance, d, from the point, P is a circle with the given point P as its center and d as its radius. Locus Theorem 2: The locus of the points at a fixed distance, d, from a line, I, is a pair of parallel lines d distance from I and on either side of I. Locus Theorem 3: The locus of points equidistant from two points, P and Q , is the perpendicular bisector of the line segment determined by the two points. Locus Theorem 4: The locus of points equidistant from two parallel lines, I1 and I2, is a line parallel to both I1 and I 2 and midway between them. Locus Theorem 5: The locus of points equidistant from two intersecting lines, I1 and I2, is a pair of bisectors that bisect the angles formed by I1 and I2.