Trapezoid
See how to solve a trapezoid
(angles/median/diagonals/area).
5 examples and their solutions.
Trapezoid: Definition
Definition
that have a pair of parallel sides.
Base: Parallel sides
Legs: Non-parallel sides
Trapezoid: Angles
Property
m∠1 + m∠2 = 180
m∠1' + m∠2' = 180
Example
x + 40 + 60 = 180
x + 100 = 180
x = 80
8y + 108 = 180
8y = 72
y = 9
x = 80, y = 9
Close
Trapezoid: Median
Definition
that connects the midpoints of the legs.
Formula
m = 12(b1 + b2)
Example
x = 12(3 + 7)
= 102
= 5
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Isosceles Trapezoid: Definition
Definition
Isosceles Trapezoid: Angles
Property
m∠1 = m∠1'
m∠2 = m∠2'
m∠[blue] + m∠[green] = 180
Example
m∠A, m∠B, m∠C = ?
Solution m∠A + 60 = 180
m∠A = 120
↓
↓
↓
m∠A = 120
m∠B = 120
m∠C = 60
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Isosceles Trapezoid: Diagonals
Formula
Example
BD = ?
Solution BD = 6 + 11
= 17
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Trapezoid: Area
Formula
A = 12(b1 + b2)h
Example
A = 12⋅(5 + 8)⋅4
= 13⋅2
= 26
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