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8.6 Trapezoids. What you’ll learn: To recognize and apply the properties of trapezoids. Solve problems involving the medians of trapezoids. Trapezoids. Trapezoids – a quadrilateral with exactly 1 pair of parallel lines. Bases – the parallel sides Legs – the nonparallel sides
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8.6 Trapezoids What you’ll learn: To recognize and apply the properties of trapezoids. Solve problems involving the medians of trapezoids.
Trapezoids Trapezoids – a quadrilateral with exactly 1 pair of parallel lines. Bases – the parallel sides Legs – the nonparallel sides Base angles – formed by a leg and a base base leg leg base Base angles Base angles
Isosceles Trapezoids A B Isosceles trapezoid – a trapezoid with congruent legs. Theorem 8.18 – Both pairs of base angles of an isosceles trapezoid are congruent. AB, CD Theorem 8.19 – The diagonals of an isosceles trapezoid are congruent. AD=BC C D
Medians of Trapezoids Median of a trapezoid – the segment that joins the midpoints of the legs of any trapezoid. Theorem 8.20, the median of a trapezoid is parallel to the bases, and its measure is one-half the sum of the measures of the bases.
ABCD is a quadrilateral with vertices A(5,1), B(-3,-1), C(-2,3), D(2,4) • Is ABCD also a trapezoid? • If it’s a trapezoid, is it an isosceles trapezoid?
DEFG is an isosceles trapezoid with median MN E F • Find DG if EF=20 and MN=30. 2. Find m1, m2, m3 and m4 if m1=3x+5, and m3=6x-5. 3 4 M N 1 2 G D