http://www.ck12.org Chapter 6. Polygons and Quadrilaterals
Example C
Findx. All figures are trapezoids with the midsegment.
Answers:
- a)xis the average of 12 and 26.^12 + 226 =^382 = 19
b) 24 is the average ofxand 35.
x+ 35
2
= 24
x+ 35 = 48
x= 13
c) 20 is the average of 5x−15 and 2x−8.
5 x− 15 + 2 x− 8
2
= 20
7 x− 23 = 40
7 x= 63
x= 9
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CK-12 Foundation: Chapter6TrapezoidsB
Concept Problem Revisited
Given an isosceles trapezoid withm^6 B= 38 ◦, find the missing angles.
In an isosceles trapezoid, base angles are congruent.
(^6) B∼= (^6) Cand (^6) A∼= (^6) D
m^6 B=m^6 C= 38 ◦
38 ◦+ 38 ◦+m^6 A+m^6 D= 360 ◦
m^6 A=m^6 D= 142 ◦
Vocabulary
Atrapezoidis a quadrilateral with exactly one pair of parallel sides. Anisosceles trapezoidis a trapezoid where the
non-parallel sides and base angles are congruent. Themidsegment (of a trapezoid)is a line segment that connects
the midpoints of the non-parallel sides.