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8-6 Trapezoids. Properties of Trapezoids. Quadrilateral with one pair of parallel sides The bases are the parallel sides The non parallel sides are legs If the legs are congruent then the trapezoid is isosceles Both pairs of base angles of an isosceles trapezoid are congruent
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Properties of Trapezoids • Quadrilateral with one pair of parallel sides • The bases are the parallel sides • The non parallel sides are legs • If the legs are congruent then the trapezoid is isosceles • Both pairs of base angles of an isosceles trapezoid are congruent • The diagonals of an isosceles trapezoid are congruent
Isosceles Trapezoid A B D C
Medians • The segment that joins the midpoints of the legs of a trapezoid • The median of a trapezoid is parallel to the bases • The measure of the median is one-half the sum of the measures of the bases A B E F D C
Example: • DEFG is an isosceles trapezoid with median MN • Find DG if EF=20 and MN=30 • Find m<1, m<2, m<3 and m<4 if m<1=3x+5 and m<3=6x-5 E F 3 4 M N 1 2 D G
G F Proof C D • CDFG is an isosceles trapezoid with bases CD and FG. Prove that