Superlesson
Project 4-2
Geometry
Chapter 4, Triangles
Triangles are used in many architectural constructions, including bridges. Below, you will examine the use of congruent triangles in bridges.
Part A, Correspondence and Congruence
1. A closer look at congruent triangles.
a. Each of the three rectangular sections (made up of the thick tubing) of the Walnut Street Bridge in Hellertown, PA contains two pairs of congruent triangles. Draw any one pair of these congruent triangles and label the vertices.
b. Write a statement indicating a triangle congruence for the triangles you drew and labeled in a.
c. Write six congruence statements for the sides and angles of the two triangles from a.
Part B, Congruent Triangles
2. Look at a picture of the Tunkhannock Creek Bridge (Nicholson Viaduct). A basic component of this bridge is a design that
looks like:
Suppose you knew the cables were the same length and the metal towers
were the same height. Which congruence postulate could you use to show 
Explain how you know.
Hint: Drawing the triangles separately may help.
Part D, Corresponding Parts
4. Look at the picture in 2 again. Suppose that the only information
you have about the Tunkhannock Creek Bridge is that its cables bisect each
other at point X. How could you prove that the medal towers are the
same height?
Hint: Prove that
first.