Download MTH 232 - Shelton State Community College

MTH 232
Section 12.1
Congruent Triangles
Overview
• Recall, from Chapter 8, that congruence is a property
applied to some geometric items (line segments and
angles) but not others (points, rays, and lines).
• We now apply the property of congruence to triangles.
• This congruence can be established by determining
congruence of certain relative parts (angles or sides) of
the triangles in question.
• It is not necessary to verify congruence of all three
sides or all three angles, as we shall see shortly.
Triangle Congruence
1. SSS (Side-Side-Side)
2. SAS (Side-Angle-Side)
3. AAS (Angle-Angle-Side)
Pictures
The Triangle Inequality
• In order for a triangle to be a triangle, the lengths of
the three sides must satisfy an important
requirement.
• The sum of the lengths of any two sides of a triangle
is greater than the length of the third side.
• Possible activity: give students three straws of
varying lengths. See how many triangle they can
construct. Then have the students measure the
straws and verify that the lengths do or do not satisfy
the Triangle Inequality.
Pictures
Modified Homework
• 1; 2; 8; 12(a), (b); 18; 38 – 42