Download IM2 Notes 6.2b

6.2(b) Notes: Proving Congruent Triangles
Lesson Objective: Prove triangles congruent
using the definition of congruence.
CCSS: G.CO.7, G.SRT.5
You will need: CPR, colored pens
Real-World App:
This is Jeopardy!!!:
Lesson 1: Third Angles Theorem
There are pairs of triangles, LMN and RST,
with matching angles.
Find the other piece of your triangle. Then
find the other matching triangle. Sketch and
label the angle measures of both triangles.
L
R
M
N
S
T
Lesson 1: Third Angles Theorem
Third Angles Theorem:
Since / L / R and / M / S, then / N / T.
L
M
R
N
S
T
Lesson 2: Use the Third Angle Theorem
If / WNX / WRX, WX bisects / NXR, m/ WNX = 88°,
and m/ NXW = 49°, find m/ NWR. Explain your
reasoning.
Lesson 3: Prove That 2 Triangles are Congruent
Write a two-column proof by listing all corresponding parts. Then give a reason for each one.
a.
Lesson 3: Prove That 2 Triangles are Congruent
Write a two-column proof.
b. The bars that give structural support to a roller
coaster form triangles.
Since the angle measures
and the lengths of the
corresponding sides are
the same, the triangles
are congruent.
Given: JK_|_KL, ML_|_KL, / KLJ / LKM, JK ML,
JL MK
Prove: ∆JKL ∆MLK
List corresponding parts:
J
K J
K
K M
/J /P
/L /L
/K /M
L JL PL
LK
KJ
LM
MP
6.2(b): Do I Get It? Yes or No
1.
6.2(b): Do I Get It? Continued
2. To write the proof, list the corresponding parts.
Give a reason for their congruency.