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Chapter 7 Chapter 7 Lesson 4Lesson 4
Objective: To find the area of a
trapezoid.
height of a trapezoid:height of a trapezoid: the perpendicular distance h between the bases.
Base
Base
LegLeghh
bb11
bb22
hh
bb11
bb22
Theorem7-10:Theorem7-10: Area of a Trapezoid Area of a Trapezoid The area of a trapezoid is half the product of the height and the sum of the bases.
)(21
21 bbhA
Example 1:Find Area of a Trapezoid
Find the area of a trapezoid with height 7 cm and bases 12 cm and 15 cm.
)1512)(7(21
A
)(21
21 bbhA
)27)(7(21
A
)27)(5.3(A
25.94 cmA
Example 2:Find Area of a Trapezoid
Find the area of a trapezoid with height 18 cm and bases 20 cm and 36 cm.
)3620)(18(21
A
)(21
21 bbhA
)56)(18(21
A
)56)(9(A
2504cmA
Example 3:Example 3:Finding Area Using a Right TriangleFinding Area Using a Right Triangle
Find the area of the trapezoid. Leave your answer in simplest radical form.
7cm7cm
)(21
21 bbhA Since you do not have the height of the trapezoid we will have to draw it in.
hh
2cm2cm 5cm5cmFind h. SLLL 3
23 h
32h
Find area. )57)(32(
21
A
)12)(32(21
A
)12)(31(A2312 cmA
5cm5cm
60°60°
5cm5cm
Example 4:Example 4:Finding Area Using a Right TriangleFinding Area Using a Right Triangle
Find the area of the trapezoid. Leave your answer in simplest radical form.
16cm16cm
)(21
21 bbhA Since you do not have the height of the trapezoid we will have to draw it in.
hh
5cm5cm 11cm11cmFind h. SLLL 3
53 h
35h
Find area. )1611)(35(21
A
)27)(35(21
A
)27)(35.2(A235.67 cmA
60°60°
11cm11cm
Assignment
Page 376-377
#1-13;21;22;24-28
