Angle Addition Sum Theorem

Each of the following relationships or properties is critical to proving the Triangle Sum Theorem EXCEPT _________.

• Substitution Property

• Angle Addition Postulate

• Linear Pair Property

Fill in statement .

Fill in reason #3.

• Substitution Property

• Transitive Property

What is the justification?

• Angle Addition Postulate

• Angle Bisector Definition

• Addition Property of Equality

• Supplement Theorem

• 23°

• 28°

• 25°

• 27°

Solve

Mathematical Equivalence

ON

Find the value of ∠A.

Mathematical Equivalence

ON

Solve

• 25°

• 125°

• 145°

• 45°

If ∠1 and ∠2 are supplementary,
then m∠1 + m∠2 = 180°.

• Supplementary Angles have a sum of 180

• Angle Addition Postulate

• Vertical Angles Theorem

• Complementary Angles have a sum of 90

• Vertical Angles Theorem 

• Angle Addition Postulate 

• Def. of congruence 

• Def. of midpoint