This document defines a trapezoid as a quadrilateral with one pair of parallel opposite sides, known as the bases, with the nonparallel sides called the legs. It defines an isosceles trapezoid as having congruent legs and notes their properties include each pair of base angles being congruent and diagonals being congruent. The document also discusses the median of a trapezoid joining the midpoints of the legs and having length equal to half the sum of the bases, and gives the formula for calculating the area of a trapezoid.

1. Trapezoids
Euclidean Geometry
High School
Math Online

2. Definition
 A trapezoid is a quadrilateral with exactly
one pair of parallel opposite sides.

3. Parts of a Trapezoid
 The parallel sides are called the bases.
 The nonparallel sides are called the legs.
leg
leg
base
base

4. Isosceles Trapezoid
 Definition: A trapezoid with congruent legs

5. Properties of Isosceles Trapezoid
 Each pair of base angles is congruent
 Diagonals are congruent

6. Median of a Trapezoid
 A segment joining the midpoints of the
legs
 Length of the median is equal to ½ times
the sum of the bases

7. Area of a Trapezoid
 Area = ½h (b1 + b2)
 H = height of the trapezoid
 B1 = one of the bases
 B2 = the other base