Exercise 4 Page 587

An equilateral triangle is a triangle with three congruent sides. To construct such a triangle, we need a compass and a straightedge. Start by drawing a segment of arbitrary length.

Next, open up the compass to the width of the segment.

If we draw two circles around the segment's endpoints, each circle will have a radius that equals the length of $\overline{AB}.$

Pick one intersection of the circles and draw segments from the intersection to $A$ and $B.$