1. TrapezoidsTrapezoids

2. Definition of a Trapezoid 1.A trapezoid is a quadrilateral with two and only two parallel sides 2.The parallel sides are called the bases 3.The nonparallel sides are called the legs Bases Legs Trapezoid

3. Isosceles TrapezoidsIsosceles Trapezoids 1.An isosceles trapezoid is a trapezoid in which the two nonparallel sides are congruent 2.Isosceles Trapezoid Theorems: 1.If a trapezoid is isosceles, then the base angles are congruent. 2.If the base angles of a trapezoid are congruent then the trapezoid is isosceles 3.If a trapezoid is isosceles, then the diagonals are congruent 4.If the diagonals of a trapezoid are congruent, then the trapezoid is isosceles A B D C

4. Median of a Trapezoid 1.The median of a trapezoid is a line segment whose endpoints are the midpoints of the nonparallel sides of the trapezoid. 2.Trapezoid Median Theorems: 1.The median of a trapezoid is parallel to the bases. 2.The length of a median of a trapezoid is equal to one-half the sum of the bases. A B D C M N

5. Useful EquationsUseful Equations

6. Trapezoid Example Given the Polygon described by: A(-2, -5), B(8,5), C(4,5), D(-2, -1) show: The length of the median is ½ the sum of the bases ABCD is a trapezoid ABCD is isosceles The median is parallel to the bases