Converse of Corresponding Angles Postulate

If 2 lines are intersected by a transversal, and corresponding angles are congruent, then the lines are parallel

converse of cointerior angle theorem

If 2 lines are cut by a transversal & cointerior angles are supplementary, then the lines are parallel.

converse of alt interior angle th

If 2 lines are cut by a transversal & alternate interior angles are congruent, then the lines are parallel

Perpendicular & Parallel Th

If 2 lines are perp 2 the same transversal, then they are parallel.

Perp & Transversal Th

If a transversal is perpendicular to one of two parallel lines, then its also perp to the other line.

trapezoid

quadrilateral with only 1 pair of parallel sides

Triangle Sum Th

the sum of the measures of the angles of a triangle is 180

Quadrilateral Sum Th

The sum of the measures of the angles of a quadrilateral is 360.

quadrilateral is parallelogram? th

If both pairs of opp angles of a quadrilateral are equal, then the quadrilateral is a parallelogram.

exterior angle theorem

An exterior angle of a triangle is equal in measure to the sum of its 2 remote interior angles.

definition of similar

Two triangles are similar iff their vertices can be matched up so that corresponding angles are equal & corresponding sides are in proportion.

definition of congruent

2 triangles are congruent iff their vertices can be matched up so tht the corresponding parts (angles & sides) of the triangles r equal in measure.

Triangle Similarity Postulate (AA Post)

If 2 angles of a triangles are equal to 2 angles of another triangle, then the 2 triangles are similar.

how to find any angle of a triangle?

A = 1/2ab sin C

trig

SOH CAH TOA

Overlapping Similar Triangles

If a line is drawn from a point on one side of a triangle parallel to another side, then it forms a triangle similar to the orinial triangle.