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Proving RightTriangles
Congruent
Free powerpoints at http://www.worldofteaching.com
The Idea of a Congruence
Two geometric figures with
exactly the same size and
shape.
F
B
A
C
E
D
How much do you
need to know. . .
. . . about two triangles
to prove that they
are congruent?
Corresponding Parts
In Lesson 4.2, you learned that if all
six pairs of corresponding parts (sides
and angles) are congruent, then the
triangles are congruent.
1. AB  DE
2. BC  EF
3. AC  DF
4.  A   D
5.  B   E
6.  C   F
ABC   DEF
Do you need all six ?
NO !
SSS
SAS
ASA
AAS
Do you need to use these
for right triangles ?
NO !
HL
HA
LL
LA
Right triangle vocabulary
Leg
hypotenuse
leg
Since you know the right angles always match you
only need two more parts to be congruent.
LL : leg - leg
LA : leg - angle
HA : hypotenuse - angle
HL : hypotenuse - leg
Name That Postulate
(when possible)
Let’s Practice
Indicate the additional information needed
to enable us to apply the specified
congruence postulate.
For ASA:
B  D
For SAS:
AC  FE
For AAS:
A  F
HW
Indicate the additional information needed
to enable us to apply the specified
congruence postulate.
A
For LA:
For LL:
B
C
D
E
F