17.)
Define the terms incenter, circumcenter, orthocenter, and centroid.
Now draw a sketch of each of these terms.

This
is the incenter of the triangle. An incenter is the point at which the
angle bisector of a triangle intersect. It is also described as the
center of the circle that can be inscribed in the triangle.

This
is the circumcenter of the triangle. A circumcenter is the point at
which the three perpendicular bisectors of each side of the triangle
intersect. It is also described as the center of the circle that can
be circumscribed about the triangle.

This
is the orthocenter of the triangle. An orthocenter is the point at which
the altitudes of a triangle intersect.

This
is the centroid of the triangle. A centroid is the point at which the
medians of the triangle intersect. It is also considered the center
of gravity of the triangle.

This
information was found at http://www.geom.uiuc.edu/~demo5337/Group2/indef.html

The
pictures were found at http://agutie.homestead.com/files/Trianglecenter_B.htm