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Parallel lines Corresponding angles postulate: If 2 parallel lines are cut by a transversal, then corresponding angles are congruent….(ie.  1   2 ) 1 2 Alternate interior angles postulate: If 2 parallel lines are cut by a transversal, then alternate interior angles are congruent….(ie.  1   2 ) Same Side interior angles postulate: If 2 parallel lines are cut by a transversal, then same side Interior angles are supplementary….(ie. m  1 + m  2=180 )

Proving lines parallel Corresponding angles postulate converse: If 2 lines are cut by a transversal such that corresponding angles are congruent, then the lines are parallel) 1 2 Alternate interior angles postulate converse: If 2 lines are cut by a transversal such that alternate interior angles are congruent, then the lines are parallel Same Side interior angles postulate converse: If 2 lines are cut by a transversal such that same side Interior angles are supplementary, then the lines are parllel (* show that m  1 + m  2=180 ) *must use one of these to prove 2 lines are parallel

Triangle sum theorem Proving Triangles Congruent 1.S-S-S (side- side-side) If 3 sides of a triangle are congruent to 3 corresponding sides of another triangle, then the triangles are congruent. 2.S-A-S (side-angle-side) 3.H-L (hypotenuse-leg) *special case for right triangles. 4.A-S-A (angle –side-angle) *all connected 5.A-A-S (angle-side-angle) *can skip one side