4.4 The Trapezoid A quadrilateral with exactly two parallel sides. The parallel sides are called the bases and the nonparallel sides are the legs. Median is the line connecting the two midpoints of the legs. Isoceles trapezoid when the two legs are congruent. Altitude is a line segment from one vertex of one base perpendicular to the opposite base (or an extension of that base). Two pairs of consecutive angles are supplementary (parallel lines cut by a transversal then the interior angles on the same side are parallel). altitude Median 9/23/2019 Section 4.4 Nack

Theorems for the Trapezoid Theorem 4.4.1: The base angles of an isoceles trapezoid are congruent. Picture proof p. 205 Ex. 2 Corollary 4.4.2: The diagonals of an isosceles trapezoid are congruent. Theorem 4.43: The length of the median of a trapezoid equals one-half the sum of the lengths of the two bases. Ex. 4, 5 p. 206 Theorem 4.4.4: The median of a trapezoid is parallel to each base. 9/23/2019 Section 4.4 Nack

Theorems of Isosceles Trapezoids Theorem 4.4.5: If two base angles of a trapezoid are congruent, the trapezoid is an isosceles trapezoid. P.207 Theorem 4.4.6: If the diagonals of a trapezoid are congruent, the trapezoid is an isosceles trapezoid. Theorem 4.47: If three (or more) parallel lines intercept congruent line segments on one transversal, then they intercept congruent line segments on any transversal. fig 4.40 p. 208 Ex. 6 9/23/2019 Section 4.4 Nack