Bolt-Circle Diameter

Module designer(s)

  • Ed Malczewski

E-mail address(es)


Cooperating teachers


  • Investigate trigonometric ratios
  • Determine the bolt circle diameter of a tire given it's chord length and vice versa
  • Investigate the connection between the circumference of a circle and PI using many sided polygons


  • Internet access
  • Geometer's Sketchpad

Related Courses

  • Geometry
  • Pre-Calculus

Links to standards

  • National Science Education Standards

Science as Inquiry

  •  NCTM Standards:

Standard 1: Mathematics as Problem Solving
Standard 2: Mathematics as Communication
Standard 3: Mathematics as Reasoning
Standard 4: Mathematical Connections
Standard 9: Geometry and Spatial Sense
Standard 13: Patterns and Relationships


Using the Geometer's Sketchpad to solve a problem often seen in automotive technology: determining the bolt circle diameter of a tire.