1. 8.5 Trapezoids

2. Vocabulary What You'll Learn
Trapezoids
What You'll Learn
You will learn to identify and use the properties of trapezoids and isosceles trapezoids.
Vocabulary
1) Trapezoid

3. A trapezoid is a ____________ with exactly one pair of ____________.
Trapezoids
A trapezoid is a ____________ with exactly one pair of ____________.
quadrilateral
parallel sides
The parallel sides are called ______.
bases
The non parallel sides are called _____.
legs
base T P A R
Each trapezoid has two pair of
base angles.
leg
leg
base angles
T and R are one pair
of base angles.
P and A are the other pair of base angles.
base

4. The median of a trapezoid is parallel to the _____, bases
Trapezoids
Theorem
8-13
The median of a trapezoid is parallel to the _____,
bases
and the length of the median equals _______________ of
the lengths of the bases.
one-half the sum C N B D M A

5. Find the length of median MN in trapezoid ABCD if AB = 16 and DC = 20
Trapezoids
Find the length of median MN in trapezoid ABCD if AB = 16 and DC = 20 16 C N D M B A 18 20

6. If the legs of a trapezoid are congruent, the trapezoid is an
Trapezoids
If the legs of a trapezoid are congruent, the trapezoid is an
_________________.
isosceles trapezoid
In lesson 6 – 4, you learned that the base angles of an isosceles triangle are
congruent.
There is a similar property of isosceles trapezoids.

7. Each pair of __________ in an isosceles trapezoid is congruent.
Trapezoids
Theorem
8-14
Each pair of __________ in an isosceles trapezoid is congruent.
base angles Z Y X W

8. Find the missing angle measures in isosceles trapezoid TRAP.
Trapezoids
Find the missing angle measures in isosceles trapezoid TRAP. T P A R
60°
P  A
Theorem 8 – 14
120°
120°
mP = mA
60 = mA
T  R
Theorem 8 – 14
60°
P + A + 2(T) = 360
(T) = 360
(T) = 360
2(T) = 240
T = 120
R = 120

9. Trapezoids
End of Section 8.5