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NOTES FOR LESSON 6-6: TRAPEZOIDS A trapezoid is a quadrilateral with exactly one pair of parallel sides. The two parallel sides are called bases. The two nonparallel sides are called legs. A pair of base angles share a common base. 1 and 2 are one pair of base angles. 3 and 4 are a second pair of base angles. The midsegment of a trapezoid is a segment connecting the midpoints of the legs. (Theorem 6-21) The midsegment is: 1) parallel to the bases and 2) its length is half the sum of the lengths of the bases. (average of the base lengths) MN = 1 (QR + ZX ) 2 An isosceles trapezoid is a trapezoid in which the legs are congruent. An isosceles trapezoid has some special properties: 1) Each pair of base angles is congruent. (Theorem 6-19) 2) The diagonals are congruent. (Theorem 6-20) Exercises 1. In trapezoid LMNO, what is the measure of OLM? What is the measure of LMN? 2. WXYZ is an isosceles trapezoid and WY = 12. What is XZ? 3. XZ is the midsegment of trapezoid EFGH. If FG = 8 and EH = 12, what is XZ? 4-5: Find the value of x and the length of each unknown leg and/or midsegment. 4. QR is the midsegment of trapezoid LMNP L 4x -10 10 5. Q M 2x + 11 M Q R x+2 N R 8x - 12 P P 8 S N NOTES FOR LESSON 6-6: KITES A kite is a quadrilateral in which two pairs of consecutive sides are congruent and no opposite sides are congruent. In a kite, the diagonals are perpendicular. (Theorem 6-22) The diagonals look like the crossbars in the frame of a typical kite that you fly. Notice that the sides of a kite are the hypotenuses of four right triangles whose legs are formed by the diagonals. Exercises In kite FGHJ in the problem, mJFK = 38 and mKGH = 63. Find the following angle and side measures. 1. mFKJ 2. mFJK 3. mFKG 4. mKFG 5. mFGK 6. mGKH 7. mKHG 8. mKJH 9. mJHK 10. If FG = 4.25, what is JF? 11. If HG = 5, what is JH? 12. If JK = 8.5, what is GJ? 13. How many pairs of congruent triangles are there in kite FGHJ? Name the pairs of triangles and state the "shortcut" (theorem/postulate) that can be used to prove each pair congruent.