By Kevin Beck | Updated Aug 30, 2022
Circles appear everywhere—from celestial bodies to everyday objects. Whether you're slicing pie, planning a garden, or creating artwork, knowing how to split a circle into equal segments is a useful skill.
Using a straightedge, draw a straight line through the circle that touches both edges. This line is the diameter and automatically divides the circle in half.
Find the midpoint of the diameter by halving its length. Mark this point; it is the center of the circle.
From the center, measure exactly one‑fourth of the diameter (or half the radius) toward one edge. Mark this point A.
Using a protractor or a right‑angle template, draw a line through A that is perpendicular to the diameter. Extend this line to intersect the circle at points B and C.
Draw straight lines from the center to points B and C. These are radii of the circle.
The two right triangles formed inside the circle are 30°–60°–90° triangles, because the short leg equals half the hypotenuse (the radius). As a result, the central angles between the radii and the diameter are each 120°, giving three equal sectors.
With this method, you can confidently divide any circle into three equal parts for cooking, design, or mathematical work.
