Download 6.5 Trapezoids

6.5 Trapezoids
Textbook page 332
A trapezoid is a quadrilateral with exactly one pair
of parallel sides.
The parallel sides of a trapezoid are called the bases.
base
base
The non parallel sides of a trapezoid are called the
legs
base
leg
leg
base
The base angles of a trapezoid are the angles
attached to the same base. (there are two pairs)
Base angle pair
base
leg
leg
base
Base angle pair
Angles on the same leg are supplementary
Base angle pair
leg
leg
Parallel lines
Same-side
interior
angles
base
Base angle pair
Add up to 1800
Add up to 1800
base
Angles on the same leg are supplementary
Parallel lines
Angles on the same leg are supplementary
Cut by a transversal
Angles on the same leg are supplementary
Same-side
interior
angles
The midsegment of a trapezoid connects the
midpoints of the legs
The midsegment of a
trapezoid is parallel to the
bases
midpoint
midsegment
The measure of the midsegment is
equal to the average of the measures of
the bases
midpoint
½ (b1 + b2)
OR
(b1 + b2)
2
The legs of an isosceles trapezoid are congruent.
Each pair of base angles in an isosceles trapezoid are
congruent.
Examples pg 333
 1) A = 800, B = 800, C = 1000
 2) A = 1100, B = 1100, D = 700
 3) B = 750, C = 1050, D = 1050
 4) 11 units
 5) 8 units
 6) 21 units
Homework
 Assignment # 14
 Pg 334
 Problems 1-26 all, 34-38 all, 39-45 odd
 Do not pack up early