Practice with Justifications

• Reflexive Propertiy

• Transitive Property

• Symmetric Property

• Substitution

If $m\angle ABC+m\angle EDF=180,\$  then
 $\angle ABC\ and\ \angle DEF$  supplementary.
Why?

• Definition of a right angle

• Definition of complementary

• Linear Pair Postulate

• Definition of supplementary

• Transitive Property

• Symmetric Property

• Reflexive Property

• Definition of congruent

If K is between L and M, then LK + KM = LM.

Why?

• Segment Addition Postulate

• Substitution

• Angle Addition Postulate

• Definition of a midpoint

 $If\ m\angle R=m\angle L,\ then\ \angle R\cong\angle L.$  
Why?

• Def. of congruent

• Def. of bisects

• Substitution

• Symmetric Prop.

• Segment Addition Postulate

• Def. of a midpoint

• Def. of bisects

• Def. of congruent

If $\angle1$ and $\angle3$  form a linear pair, 

then they are supplementary

• Linear Pair Postulate

• Def of supplementary

• VAT

• Def of linear pair

IF $\ \overline{PQ}\cong\overline{RE},$ then PQ = RE.

Why? 

• Definition of congruent

• Reflexive Prop.

• Symmetric Prop.

• Def. of a midpoint

• Def. of complementary

• Def. of a right angle

• Def. of supplementary

• Angle Addition Postulate

• Reflexive Property

• Transitive Property

• Symmetric Property

• Substitution Property