The line equations are
and
.
Graph :
\Graph the line equations
and
.
.gif\")
Observe the graph :
\Point of intersection are
and
.
Find the mid point of the system.
\Mid point :
.
Mid point of the points
and
.

.
Mid point of the points
and
.

.
Mid point of the points
and
.

.
The mid point of the systems are
,
and
.
Find the perpendicular bisectors.
\Perpendicular bisectors are the lines equation that are perpendicular to the given line equation.
\1.
\The line equation is
.

Slope of the line is
.
Slope of the perpendicular bisector is
.
The equation of perpendicular bisectors are in the form of
.
Substitute
and
in the
.

Substitute
and
in the perpendicular bisector equation.
Perpendicular bisector equation is
.
2.
\The line equation is
.

Slope of the line is
.
Slope of the perpendicular bisector is
.
Substitute
and
in the
.

Substitute
and
in the perpendicular bisector equation.
Perpendicular bisector equation is
.
3.
\The function
.

Slope of the line is
.
Slope of the perpendicular bisector is
.
Substitute
and
in the
.

Substitute
and
in the perpendicular bisector equation.
Perpendicular bisector equation is
.
Graph :
\Graph the equations
,
and
.
(1).gif\")
Observe the graph :
\The three lines intersects at
.
The point
is the center of the circle.
The radius of the circle is the distance between the point and vertex.
\Vertex
and point is
.

.
The standard form of the equation of the circle is
.
Substitute
,
and
.

Graph :
\Graph the line equations
and
.
\
Graph the circle
.
.gif\")
The equation of the circle circumference of the triangle
.