Download 4.1 Congruent Figures Congruent Figures: Have the same size and

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Transcript
4.1 Congruent Figures
Congruent Figures: Have the same size and shape
Corresponding sides and corresponding angles are congruent
Congruence Statements:
For the two congruent triangles, we can write the following:
∆ABC ≅ ∆FED or ∆BCA ≅ ∆EDF or ∆CAB ≅ ∆DFE
(Note: Must be written in correct order!!)
Corresponding angles:
∠A ≅ ∠F
∠B ≅ ∠E
∠C ≅ ∠D
Corresponding sides:
̅̅̅̅
̅̅̅̅ ≅ ̅̅̅̅
𝐴𝐵 ≅ ̅̅̅̅
𝐹𝐸
𝐵𝐶
𝐸𝐷
̅̅̅̅
𝐶𝐴 ≅ ̅̅̅̅
𝐷𝐹
Yes (3rd angles theorem and reflexive prop)
(Order matters!!)
No (Corresponding sides are not congruent)
X + 10 = 2x
3z + 2 = z + 6
x = 10 m<A and m<D = 20
2z = 4
z=2
BC and EF = 8
4.2 Triangle Congruence by SSS and SAS
Statements
FJ congruent to HJ
G is mdpt FH
FG congruent to GH
JG congruent to JG
∆FGJ congruent to ∆HGJ
Reasons
Given
Given
Def midpt
Reflexive
SSS Congruence
SSS, SAS, or not enough info?
4.3 Triangle Congruence by ASA and AAS
Statements
Reasons
< B and <D are right angles
Given
̅̅̅̅
̅̅̅̅
𝐴𝐸 bisects 𝐵𝐷
Given
<B ≅ <D
Right angles are ≅
<BCA ≅ <DCE
Vertical angles
̅̅̅̅ ̅̅̅̅̅̅̅̅
𝐵𝐶
≅ 𝐷𝐶
Definition of bisector
∆𝐴𝐵𝐶 ≅ ∆𝐸𝐷𝐶
ASA
AAS
Not enough info
ASA
SAS
4.4 Using Corresponding Parts of Congruent Triangles
What is the definition of congruent triangles?
Corresponding parts of congruent triangles are congruent. (CPCTC)
Why are they congruent?
SAS
What else can we conclude?
̅̅̅̅ ≅ 𝐷𝐹
̅̅̅̅
< A ≅ <D, <C ≅ <F 𝐴𝐶
Statements
Reasons
̅̅̅̅ , ̅̅̅
̅̅̅
𝐽𝐾 ‖𝑄𝑃
𝐽𝐾 ≅ ̅̅̅̅
𝑃𝑄
Given
<J ≅ <P
Alternate Interior Angles
<KMJ ≅ <QMP
Vertical Angles
∆𝐾𝑀𝐽 ≅ ∆QMP
AAS
̅̅̅̅
𝐽𝑀 ≅ ̅̅̅̅̅
𝑃𝑀
CPCTC
M is a midpoint
Def. of midpoint
̅̅̅̅ bisects ̅̅̅
𝐾𝑄
𝐽𝑃
Def. of segment bisector
4.5 Isosceles and Equilateral Triangles
Isosceles Triangle: A triangle with 2 congruent sides
̅̅̅̅ and 𝐵𝐶
̅̅̅̅
Legs: 𝐴𝐶
Vertex angle: ∠C
̅̅̅̅
Base: 𝐴𝐵
Base angles: ∠A and ∠B
70
75
x = 40 y = 70
X = 60 y = 120
4.6 Congruence in Right Triangles
Right Triangle:
Statements
̅̅̅̅
𝑄𝑆 ≅ ̅̅̅̅
𝑃𝑅
Reasons
̅̅̅̅
̅̅̅̅  ̅̅̅̅
𝑃𝑆  ̅̅̅̅
𝑅𝑆 , 𝑄𝑅
𝑅𝑆
Given
<S and < R are right angle
Def. of Perpendicular
∆PRS and ∆QSR are right ∆′𝑠
Def. of right ∆
̅̅̅̅
𝑅𝑆 ≅ ̅̅̅̅
𝑅𝑆
Reflexive Prop.
∆PRS ≅ ∆QSR
HL