Step 1

Using a straightedge, draw an obtuse triangle. Label the vertices asA,

B,

andC.

Step 2

Draw the perpendicular bisector of sideAC.

Place the compass point onA,

then set the width of the compass so that the distance is slightly longer than half the length ofAC. Then draw an arc that passes through AC and has endpointsabove and below pointA.

Keep the compass setting and place the point of the compass at pointC,

then draw an arc that passes through AC and has endpointsabove and below pointC.

The intersection of these arcs constructs two points. Label these pointsD

andE.

Using a straightedge, drawDE.

Step 3

Draw the perpendicular bisector of side BC.

Place the compass point onB,

1. then set the width of the compass so that the distance is slightly longer than half the length ofBC. Then draw an arc that passes throughBC and is above and below pointB.

Keep the compass setting and place the point of the compass at pointC,

then draw an arc that passes through BC and is above and below pointB.

The intersection of these arcs constructs two points. Label these pointsF

andG.

Using a straightedge, drawFG.

Step 4

Mark the intersection ofDE and FG. Label this pointH.

Then place the point of the compass at pointH,

and set the width of the compass to one of the vertices of ABC and draw a circle. If you did the construction correctly, this circle intersects each vertex of the triangle.