1. Essential Quote: It’s a trap!
8-5: Trapezoids
Essential Quote: It’s a trap!

2. 8-5: Trapezoids
Trapezoid: A quadrilateral with exactly one pair of parallel sides.
Bases: The pair of parallel sides in a trapezoid
Legs: The nonparallel sides of a trapezoid
Base Angles: Pairs of angles that lie on the same base.
base angles
base
leg
leg
base
base angles

3. 8-5: Trapezoids
Median: The segment that joins the midpoints of the legs.
The median of a trapezoid it equal to one half the sum of the two bases
Example: Find MN if DE = 12 and FG = 18
½( )
½(30)
MN = 15 D E
MN = ½(DE + GF) M N G F

4. 8-5: Trapezoids
In some case, you will be asked to find the length of a leg given the median and the other leg
Example: Find FG if MN is a median, MN = 22 and DE = 14
22 = ½(14 + FG)
44 = 14 + FG
FG = 30 D E
MN = ½(DE + GF) M N G F

5. 8-5: Trapezoids
ISOSCELES TRAPEZOID: A trapezoid where the two legs are congruent.
In this case, each pair of base angles are congruent.
Example: Find the missing angles in trapezoid TRAP
P and A are base angles
Since this is an isosceles trapezoid, the base angles are equal
P = 60
T and R are also equal
A trapezoid is a quadrilateral, meaning its angles add up to 360˚.
x + x = 360
2x = 360 (combine like terms)
2x = (subtract 120 each side)
x = (divide by 2)
T = 120 and R = 120

6. 8-5: Trapezoids
Assignment
Worksheet 8-5