Chapter 16 · ICSE Class 10 Mathematics (Selina Concise)

Loci & its Constructions

Understand loci as paths satisfying a geometric condition, and construct the locus of points equidistant from given references.

📐 Chapter 16

The locus of points equidistant from two fixed points A and B is the perpendicular bisector of AB Two points A and B connected by a line, with a dashed perpendicular line crossing the midpoint of AB at a right angle, representing the set of all points equally distant from A and B A B Locus: equidistant from A and B
16.1

Common Loci Definitions

The locus of points equidistant from two fixed points is the perpendicular bisector of the segment joining them. The locus of points equidistant from two lines is the angle bisector.

1

What is the locus of points equidistant from points A and B?

The perpendicular bisector of segment AB

2

What is the locus of points equidistant from two intersecting lines?

The bisectors of the angles formed by the two lines

16.2

Locus at a Fixed Distance

The locus of points at a fixed distance from a point is a circle. The locus of points at a fixed distance from a line is a pair of parallel lines.

1

What is the locus of points 5 cm from a fixed point O?

A circle of radius 5 cm centred at O

2

What is the locus of points 3 cm from a given line l?

Two lines parallel to l, one on each side, 3 cm away

Practice

Exercises

1. What is the locus of points equidistant from two fixed points P and Q?

2. What is the locus of points 6 cm from a fixed point?

3. What is the locus of points equidistant from the two arms of an angle?

4. What is the locus of points 4 cm from a given line?

5. A point moves so it's always 5 cm from a fixed line. What shape does the locus form?

Next chapter — Circles ⭕ →