We construct the circumcenter of ∆ABC as follows. Construct the midpoints L, M, and N ofthe sides opposite the vertices A, B, and C,respectively.
Construct the line through L perpendicular to segment BC, i.e. the perpendicular bisector of BC. Similarly, construct the perpendicular bisectors of AC
and AB. These lines pass through points M and N, respectively. The three
perpendicular bisectors are concurrent, meeting at point O, the circumcenter of
∆ABC. See Figure 2.