Step-by-step explanation:
The solution is in the attached file
Answer:
1) supplementary
2) ∠ABD = 180° - 123°
Step-by-step explanation:
Answer:
Theorem.
Step-by-step explanation:
Postulate/Axiom: Can't be proven or disproven.
Definition: Defines a term. Can be proven.
Theorem: Can be proven.
"Proof" (informal but it works): Triangle has 180°, that means two angles will be less than 180°. Right angles are 90°, that means two 90° angles add up to 180°. Something that is less than 180° is less than 180°.
This statement is provable, but doesn't necessarily define anything.
