1. 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)
altitude
Median
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2. 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 p. 206
Theorem 4.4.4: The median of a trapezoid is parallel to each base.
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3. 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. 207
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