ProveIt! Two-Column Proofs Practice Tool

Proof: Triangle Sum Theorem 3

AFB = 60 $\^o$

BCD = 30 $\^o$

line AB

perpendicular

line AD

line AB $\|\|$ line DC

1.

1.

line AB $\|\|$ line DC

CDA = 90 $\^o$

AFB +

BCD +

CDA = 180 $\^o$

60 $\^o$ + 30 $\^o$ +

CDA = 180 $\^o$ ; 90 $\^o$ +

CDA = 180 $\^o$

line AB

perpendicular

line AD

AFB = 60 $\^o$

line DC

perpendicular

line AD

BCD = 30 $\^o$

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