Geometry: An Interactive Journey to Mastery



Lesson 8: Proofs and Proof Writing

1. *LYHQ.
   .
   ab
   dc

‘#‘

‘#‘

Prove: AB DE||.

ͼ௘6HHFigure 8.3௘ͽ

2. *LYHQ PSASR.
   ‘a and ‘cDUHFRPSOHPHQWDU\
   Prove: ‘#‘bc.
   ͼ௘6HHFigure 8.4௘ͽ


3. *LYHQ ||.
   ||.

AB CD

AD BC

Prove: ‘#‘AC.

ͼ௘6HHFigure 8.5௘ͽ

4. *LYHQ UFAUM.
   Prove: FM!LM.
   ͼ௘6HHFigure 8.6௘ͽ

Problems

A

B

C

D

E

a b

d

c

Figure 8.3

Figure 8.4

P

Q

R

S a

bc

Figure 8.5

A

D

B

C

Figure 8.6

F

U

L

M