Transcript Lesson_4.1_Congruent_Figures - Mustang-Math

(4.1) Congruent Figures
There’s no crying in baseball!
-Jimmy
Unit 4 Congruent Triangles ~ Standards
4.1 Objects in the plane can be transformed, and
those transformations can be described and
analyzed algebraically.
Prove geometric theorems (Lines, Angles,
Triangles, Parallelograms)
Unit 4 Congruent Triangles ~ Lesson Target:
To recognize congruent figures and their
corresponding parts.
Congruent Figures
Congruent Polygons: Congruent polygons are polygons that have
corresponding sides that are congruent and corresponding angles
that are congruent.
Ex. Of corresponding:
C correspond s to R
B corresponds to Q
AX corresponds to PY

B  Q C  R A  P X  Y
AX  PY

XB  YQ
BC QR
ACBX  PRQY
CA  RP
Congruent Figures
To be congruent, figures must have the same:
 Shape
 Size
 You can slide, flip or turn them so that one fits
exactly over the other
Congruent Figures
ABC  QRS.
Draw and List the congruent corresponding parts.
Congruent Figures
Given that the following pentagons are congruent, find the
value of B.
C
A
R
W
132°

B
E
95°
S
P
T
D
Congruent Figures
92°
40°
Theorem 4-1: If two angles of one triangle are congruent to
two angles of another triangle, then the third angles are
congruent.
C  F
Since A  D


and B  E
then C  F
Congruent Figures
Decide whether the triangles are congruent. Justify!
E
3
B
4
C
3
A
4
D
Proving Triangles Congruent
Given : PS  PQ
Prove : PQR  PSR
QR  SR
Q  S
QPR  SPR
Statements
Reasons
1. PS  PQ ; QR  SR
1.
2.
2. Reflexive Property
3. Q  S ;QPR  SPR
3.
4. QRP  SRP
4.
5.
5.
Definition of
 polygons
(4.1) Congruent Figures
Homework:
(4.1) Pgs. 200- 202; 3-12 all,16-27 all, 30-32
all, 34, 44 Due: Thurs.