Polygonal Construction, ContinuedTriangles(Continued)You may also use a protractor to construct triangles.To use a protractor or semicircular protractor to construct an equilateraltriangle, use this table:StepAction1With a straightedge, draw a line (AB) at any convenient length anda perpendicular line at the center.2Place the center of the protractor (usually marked 0) at A, align theprotractor with the line AB.3Locate the 60° increment on the protractor and lightly mark yourpaper. If using a full circular protractor, you can increase accuracyby also locating and marking the opposing angle. This allows youto use the four-point reference system (DM Volume 1, chapter 2).4Move the protractor to B on line AB. Locate and mark the drawingat the 60º increment. Also mark the opposing angle , if possible.5Draw straight lines through the marked increments terminating atthe perpendicular line. These lines should intersect forming anequilateral triangle.Figure 2-38 shows an equilateral triangle constructed by using a protractor.Figure 2-38.—Constructing anequilateral triangle with a protractor.Continued on next page2-39