1) List the five ways to prove two triangles congruent.2) Complete each sentence below: Class starts when the _______________.

• We do not _____________when the teacher is talking.

___________________are to be treated with respect.

Bell Work

MNKΔLJK

Lets use CPCTC!

Objective: Be able to use CPCTC to find unknowns in congruent triangles!

Are these triangles congruent? By which postulate/theorem?

_____ _____

J

L

K N

M

Oh, and what is the Reflexive Property again?

It says something is equal to itself. EX

We learn by doing, and in the process you're going to fall on your face a few times... though I didn't think you'd take it quite that literally.

C.P.C.T.C.

Once you have shown triangles are congruent, then you can make some CONCLUSIONS about all of the

corresponding parts (_______ and __________) of those triangles!

Corresponding Parts of Congruent Triangles are CONGRUENT!!

C.P.C.T.C.

sides angles

Are the triangles congruent? By which postulate or theorem?

What other parts of the triangles are congruent by CPCTC?

A

B

C

X

Y

Z

If <B= 3x and ,Y = 5x –9, find x.

Yes; ASA

3x = 5x - 9

9 = 2x

x2

9

2. _______________ 2. ReflexiveCSCS

43

Given:

SRSL21

Prove: 3 4

4. _______________ 4. ___________

L

SR

C

1 2

3 4

Given

SAS

CPCTC

C

A

R

V

E

H

Given:

VECAEHAR HVRC

Prove: HR

1. _____________________ 1. Given

2. _____________________ 2. SSS

3. _____________________ 3. ________

VECA;EHAR ;HVRC

VHECRA

HR CPCTC

State why the two triangles are congruent and write the congruence statement. Also list the other pairs of parts that are congruent by CPCTC.

C

T

Y

R

P

Q

AAS

A geometry class is trying to find the distance across a small lake. The distances they measured are shown in the diagram. Explain how to use their measurements to find the distance across the lake.

30 yd

30 yd

40 yd24.5 yd

40 yd

The triangles are congruent by SAS.

Vertical angles are congruent.

The width of the lake has to be 24.5 yd by CPCTC.

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