a line that intersects two coplaner lines at two different points
5 steps for writing a DEDUCTIVE PROOF
1. REWRITE the conjecture to be proved in if-then form. 2. DRAW and label a figure to represent the given info. 3. STATE the statement to be proved in terms of the figure.
Steps 4 and 5 of DEDUCTIVE PROOF
4. PLAN the proof. (find a logical sequence of steps that shows why the conjecture must be true.) DEMONSTRATE the argument by translating your plan into writing. Every statement you make must be justified with a reason.
Alternate interior angles postulate
If parallel lines are cut by a transversal, then the alternate interior angles are congruent
3 Theorems of parallel lines
1. If parallel lines are cut by a transversal, then the corresponding angles are congruent. 2. If parallel lines are cut by a transversal, then the alternate exterior angles are congruent 3. same "" same-side interior angles are supplementarty.