1. Similarity and Parallelograms

2.  Polygons whose corresponding side lengths are proportional and corresponding angles are congruent.

3.  Ratio of the lengths of two corresponding sides (always reduce)

4.  If two polygons are similar then the ratio of their perimeters is equal to the ratios of the corresponding side lengths.

5.  If the lines are parallel, then alternate interior angles are congruent. (Look for Z)  If the lines are parallel, then corresponding angles are congruent. (Look for F)  If the lines are parallel, then consecutive interior angles are supplementary. (C – supp)

6.  AA~  SAS~  SSS~

7.  If two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.

8.  If an angle of one triangle is congruent to an angle of another triangle and the lengths of the sides including these angles are proportional, then the triangles are similar.

9.  If the lengths of the corresponding sides of two triangles are proportional, then the triangles are similar.

12.  If a triangle has two congruent sides, then the angles opposite those sides are congruent.  Or Base angles of an isosceles triangle are congruent.

13.  It is a quadrilateral with two pair of opposite sides parallel.

14.  Opposite sides are parallel.  Opposite sides are congruent.  Opposite angles are congruent.  Consecutive angles are supplementary.  Diagonals bisect each other.

15.  A quadrilateral with four right angles. What is another property of a rectangle? Answer: The diagonals are congruent.

16.  A quadrilateral with four congruent sides. What is a special property of a rhombus? Diagonals are perpendicular.

17.  A median is a segment from a vertex of a triangle to the midpoint of the opposite side.

18.  At a point called the centroid

19.  From the vertex to the centroid of the triangle is 2/3 the length of the median.

20.  The segment that joins the midpoint of two sides of a triangle is parallel to the third side and is ½ the length of the third side. What does x equal? 3

21.  The length of the segment that joins the midpoints of the legs of a trapezoid is ½ the length of the sum of the bases.