Congruent line segments

Two segments are congruent (≅) if they have the same length.

Introduction:

  • Definition of Congruence: In geometry, the term “congruence” indicates that two geometric figures are identical in shape and size. When it comes to line segments, congruence implies that two segments have the same length.
  • Congruent Line Segments: Line segments are congruent if they have equal lengths. This concept is fundamental in geometry and plays a crucial role in various geometric proofs and constructions.

Properties of Congruent Line Segments:

  1. Equal Lengths:
    • The most fundamental property of congruent line segments is that they have the same length.
    • If AB and CD are congruent line segments, then the measure of AB is equal to the measure of CD.
  2. Symbolic Representation:
    • Congruent line segments are often denoted using the symbol ≅.
    • For example, if ABCD, it signifies that line segments AB and CD are congruent.

Methods of Proving Congruent Line Segments:

  1. Measurement:
    • Direct measurement using a ruler is the simplest way to show that two line segments are congruent.
  2. Congruence Postulates:
    • Side-Side-Side (SSS) Congruence Postulate: If three sides of one triangle are congruent to three sides of another triangle, the triangles are congruent.
    • Side-Angle-Side (SAS) Congruence Postulate: If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, the triangles are congruent.

Learn with an example

  • yes
  • no

Look at the diagram and compare WX to UY .

WX is 82 Centimeters long and UY is 82 Centimeters long . WX and UY have the same length , so WX and UY are congruent .

  • yes
  • no

Look at the diagram and compare EF to FG .

EF is 165 millimeters long and FG is 165 millimeters long . EF and FG have the same same length , so EF and FG are congruent

  • yes
  • no

Look at the diagram and compare IJ to GH .

IJ = 131 and GH = 166 . IJ ≠ GH , so IJ and GH are not congruent .

let’s practice!