Midsegments of a Triangle
Lab (paper-folding)
1. Draw a triangle on a piece of paper, label the triangle VABC . You want the
triangle to take up approximately half of the paper. Use a black marker so it is easy
to see your triangle when you make the folds. Using scissors, cut the triangle out
leaving approximately a one-inch margin around the outside of your triangle.
Hint: You may want to have students work in groups of 2 or 3, and each group is
responsible for making an acute, right and obtuse triangle with midsegments.
B
C
A
2. Fold A onto B and mark the midpoint of
AB .
Label the midpoint of
AB point X.
3. Fold B onto C and mark the midpoint of
BC .
Label the midpoint of
BC
point Y.
4. Fold A onto C and mark the midpoint of
AC .
Label the midpoint of
AC
point Z.
B
Y
X
C
Z
A
5. Using a straightedge, construct
such as red and a dotted line.
XY ,YZ and XZ . You should use a different color
B
Y
X
C
A
Geometry – Triangles
Z
~1~
NJCTL.org
Questions
1. Measure the lengths of the segments and fill out the chart below. Use a ruler to
measure the length of the segments.
Side
Length
AB
BC
AC
XY
YZ
XZ
2. Use a calculator to find the following ratios.
Record your answers below:
AB/YZ
BC/ XZ
AC/XY
Ratio
3. Find the perimeter ABC and VXYZ by adding the sides of each triangle. Use
a calculator to find the ratio of the perimeters.
VXYZ
VABC
PerimeterVABC
PerimeterVXYZ
Perimeter
4. Use a protractor to measure the angles and fill out the chart below.
m<BAC
m<ABC
m<BXY
m<ZYC
m<XYZ
m<XZY
m<YZC
m<AXZ
m<BCA
m<BYX
m<YXZ
m<XZA
5. What segments are parallel and why?
6. What triangles are congruent and why?
Geometry – Triangles
~2~
NJCTL.org