Using Using Congruent Congruent Triangles Triangles

Part 1Part 1

11/03/2011

Proof FormatProof Format• When using CPCTC to prove that

corresponding parts of a triangle are congruent, we use the same general format:oDetermine the 3 pieces of congruency

based on the given information and the diagram

oDetermine what the two congruent triangles are and the method of congruence

oUse CPCTC to prove the corresponding parts.

Complete the following Complete the following

proof:proof:

Statements Reasons

1. DF bisects <EDG

DE = DG

2. <1 = <2

3. DF = DF

4. ∆ = ∆

5.

Complete the following proof:Complete the following proof:

Statements Reasons

1. PR=SR; PQ=SQ

1. Given

2. QR=QR 2. Reflexive

3. ∆PQR= ∆SQR 3. SSS Postulate

4. <P=<S 4. CPCTC

Complete the following Complete the following

proof:proof:Statements Reasons

1. C is the midpoint of AD; <A=<D

1. Given

2. AC=CD 2. Def. of a Midpt.

3. <ACB=<DCE 3. Vertical Angles

4. ∆ABC= ∆DEC 4. ASA Postulate

5. BC=EC 5. CPCTC

Complete the following Complete the following

proof:proof:Statements Reasons

1. WY is perp. To XZ; XY=YZ

1. Given

2. <XYW=<ZYW 2. If 2 lines are perp. Then they form = adj. <s

3. WY=WY 3. Reflexive

4. ∆XYW= ∆ZYW 4. SAS Postulate

5. <X=<Z 5. CPCTC