Transcript Perimeter, Circumference, and Area LESSON 1-9 Additional Examples Margaret’s garden is a square 12 ft on each side. Margaret wants a path 1 ft.

Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
Margaret’s garden is a square 12 ft on each side.
Margaret wants a path 1 ft wide around the entire garden.
What will the outside perimeter of the path be?
Because the path is 1 ft wide, increase each side
of the garden by 1 ft. s = 1 + 12 + 1 = 14
P = 4s
Formula for perimeter of a square
P = 4(14) = 56
Substitute 14 for s.
The perimeter is 56 ft.
Quick Check
HELP
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
. G has a radius of 6.5 cm. Find the circumference of . G in
terms of . Then find the circumference to the nearest tenth.
C=2 r
Formula for circumference of a circle
C = 2 (6.5)
Substitute 6.5 for r.
C = 13
Exact answer
C = 13
Use a calculator.
The circumference of . G is 13 , or about 40.8 cm.
HELP
Quick Check
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
Quadrilateral ABCD has vertices
A(0, 0), B(9, 12), C(11, 12), and D(2, 0).
Find the perimeter.
Draw and label ABCD on a coordinate plane.
Find the length of each side. Add the lengths to find the perimeter.
AB =
=
(9 – 0)2 + (12 – 0)2 =
92 + 122
81 + 144 = 255 = 15
BC = |11 – 9| = |2| = 2
CD =
=
(2 – 11)2 + (0 – 12)2 =
81 + 144 = 255 = 15
DA = |2 – 0| = |2| = 2
HELP
Use the Distance Formula.
Ruler Postulate
(–9)2 + (–12)2
Use the Distance Formula.
Ruler Postulate
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
(continued)
Perimeter
= AB + BC + CD + DA
= 15 + 2 + 15 + 2
= 34
The perimeter of quadrilateral ABCD is 34 units.
Quick Check
HELP
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
To make a project, you need a rectangular piece
of fabric 36 in. wide and 4 ft long. How many square feet of fabric do
you need?
Write both dimensions using the same unit of measurement. Find the
area of the rectangle using the formula A = bh.
36 in. = 3 ft
Change inches to feet using 12 in. = 1 ft.
A = bh
Formula for area of a rectangle.
A = (4)(3)
Substitute 4 for b and 3 for h.
A = 12
You need 12 ft2 of fabric.
HELP
Quick Check
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
Find the area of . B in terms of
.
In . B, r = 1.5 yd.
A=
r2
Formula for area of a circle.
A=
(1.5)2
Substitute 1.5 for r.
A = 2.25
The area of . B is 2.25
yd2.
Quick Check
HELP
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
Find the area of the figure below.
Draw a horizontal line to separate the figure into three
nonoverlapping figures: a rectangle and two squares.
HELP
GEOMETRY
Perimeter, Circumference, and Area
LESSON 1-9
Additional Examples
(continued)
Find each area. Then add the areas.
AR = bh
AR = (15)(5)
AR = 75
Formula for area of a rectangle
Substitute 15 for b and 5 for h.
AS = s2
AS = (5)2
AS = 25
Formula for area of a square
Substitute 5 for s.
A = 75 + 25 + 25
A = 125
Add the areas.
The area of the figure is 125 ft2.
HELP
Quick Check
GEOMETRY