Chapter 13: Constructions

Basic Constructions

Tools Needed

  • Compass
  • Ruler (straightedge)
  • Pencil

Construction 1: Bisect an Angle

  1. Draw arc from vertex cutting both arms
  2. From intersection points, draw equal arcs
  3. Join vertex to intersection of arcs

Construction 2: Perpendicular Bisector

  1. Open compass more than half the line
  2. Draw arcs from both endpoints
  3. Join intersection points

Construction 3: 60° Angle

  1. Draw a ray
  2. With same radius, draw arc
  3. Mark equal arc to get 60°

Construction 4: 90° Angle

  1. Construct 60° angle
  2. Bisect 60° to get 30°
  3. Or draw perpendicular to line