Medians and Lengths in Trapezoids
Learn about trapezoids, isosceles trapezoids, and medians. Discover the properties of medians and how to find their lengths. Solve homework problems related to trapezoids.
Medians and Lengths in Trapezoids
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Presentation Transcript
Geometry 5.5 Trapezoids
Trapezoid (Defn.)Memo about medians A quadrilateral with exactly one pair of parallel sides. leg The sides are called the bases base base The other sides are called the legs leg
IsoscelesTrapezoid (Defn.) A trapezoid with congruent legs.
Theorem Base angles of an isosceles trapezoid are congruent.
Median of a Trapezoid (Defn.) A segment that joins the midpoints of the legs. median leg leg
Theorem The median of a trapezoid: 1. is parallel to the bases. 2. has a length equal to the average of the base lengths. A B XY = ½(AB + CD) median X Y C D
B B A A F F E E D D C C
B B A A F F E E D D C C
B B A A F F E E D D C C
Homework pg. 192-193 CE 1-11 WE 1-18
Example Find the length of the median of the trapezoid. Median = ½(Base 1 + Base 2) 5x = 25 ½ [(x + 12) + (7x – 2)] x + 12 5x = (2) 5x = 8x + 10 5x 10x = 8x + 10 2x = 10 x = 5 7x -2
A few homework problems…. Let’s do P. 192-193 #8 and #15