NB Math Dictionary

An acute angle is an angle less than 90 degrees.

These are two non-adjacent interior angles on opposite sides of a transversal.

Two non adjacent interior angles on opposite sides of a transversal 

alternate interior angles is 

corresponding angles is 

Circular reasoning is when you attempt to make an argument by beginning with an assumption that what you are trying to prove is already true

A testable expression that is based on available evidence but is not yet proved.

A statement that is formed by switching the premise and the conclusion of another statement.

corresponding angles One interior angle and one exterior angles that are non-adjacnt and on the same said of a transversal

An example that invalidates a conjecture.

That is, an example that proves a conjecture to be false. 

Drawing a specific conclusion through logical reasoning by starting with general assumptions that are known to be valid.