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Properties of Trapezoids and Kites. Geometry H2 (Holt 6-6) K. Santos. Kite. Kite—a quadrilateral with exactly two pairs of consecutive sides congruent A B D C. Theorem 6-6-1.
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Properties of Trapezoids and Kites Geometry H2(Holt 6-6) K. Santos
Kite Kite—a quadrilateral with exactly two pairs of consecutive sides congruent A B D C
Theorem 6-6-1 If a quadrilateral is a kite, then its diagonals are perpendicular. A B D C
Theorem 6-6-2 If a quadrilateral is a kite, then exactly one pair of opposite angles are congruent. A B D C <B <D
Other Kite Observations --adjacent sides congruent --no parallel sides --1 pair opposite angles congruent --diagonals perpendicular --one diagonal bisects angles formed by adjacent sides --one diagonal is bisected --symmetry about one diagonal --two sets of congruent right triangles
Kite Example Find all the missing angles. 50 70
Trapezoid Trapezoid—a quadrilateral with exactly one pair of opposite sides parallel A B D C Bases: parallel sides and Legs: non-parallel sides and
Isosceles Trapezoid Isosceles Trapezoid—a trapezoid with congruent legs (non-parallel sides) A B D C
Theorem 6-6-3 If a quadrilateral is an isosceles trapezoid, then each pair of base angles are congruent. B C A D Given: ABCD is an isosceles trapezoid Then: < B < C < A < D
Theorem 6-6-4 If a trapezoid has one pair of congruent base angles then the trapezoid is isosceles. A D B C Given: < B < C Then: ABCD is an isosceles trapezoid
Theorem 6-6-5 A trapezoid is isosceles if and only it its diagonals are congruent. B C A D Given: ABCD is an isosceles trapezoid Then:
Example—Trapezoid--angles WXYZ is an isosceles trapezoid, m< X = 156. Find m < Y, m < Z and m < W. W Z X Y
Example—Trapezoid--Diagonals AD = 12x -11 and BC = 9x - 2. Find the value of x so that ABCD is an isosceles trapezoid. A B C D
Midsegment of a trapezoid Midsegment of a trapezoid—is the segment whose endpoints are the midpoints of the legs. R S M N U T is the midsegment
Trapezoid Midsegment Theorem (6-6-6) The midsegment of a trapezoid is parallel to each base, and its length is one half the sum of the bases. S T M N R U |||| MN = (average of the parallel bases)
Example--Midsegment Find x. 8 x 14
Example--Midsegment Find EH. F 25 G X 16.5 Y E H
Example—Midsegment (algebraic) Find the length of the midsegment. n + 2 n + 10 3n - 12