Post on 30-Dec-2015
Holt McDougal Geometry
7-5 Using Proportional Relationships7-5 Using Proportional Relationships
Holt GeometryHolt McDougal Geometry
Holt McDougal Geometry
7-5 Using Proportional Relationships
Warm UpConvert each measurement.
1. 6 ft 3 in. to inches
2. 5 m 38 cm to centimeters
Find the perimeter and area of each polygon.
3. square with side length 13 cm
4. rectangle with length 5.8 m and width 2.5 m
Holt McDougal Geometry
7-5 Using Proportional Relationships
Whenever dimensions are given in both feet and inches, you must convert them to either feet or inches before doing any calculations.
Helpful Hint
Holt McDougal Geometry
7-5 Using Proportional RelationshipsTyler wants to find the height of a telephone pole. He measured the pole’s shadow and his own shadow and then made a diagram. What is the height h of the pole?
Holt McDougal Geometry
7-5 Using Proportional Relationships
A student who is 5 ft 6 in. tall measured shadows to find the height LM of a flagpole. What is LM?
Holt McDougal Geometry
7-5 Using Proportional Relationships
• A scale drawing represents an object as smaller than or larger than its actual size.
• The drawing’s scale is the ratio of any length in the drawing to the corresponding actual length.
• For example, on a map with a scale of 1 cm:1500 m, one centimeter on the map represents 1500 m in actual distance.
Holt McDougal Geometry
7-5 Using Proportional Relationships
On a Wisconsin road map, Kristin measured a
distance of 11 in. from Madison to Wausau.
The scale of this map is 1inch:13 miles. What
is the actual distance between Madison and
Wausau to the nearest mile?
Holt McDougal Geometry
7-5 Using Proportional Relationships
Find the actual distance between City Hall and El Centro College.
Holt McDougal Geometry
7-5 Using Proportional Relationships
Lady Liberty holds a tablet in her left hand. The tablet is 7.19 m long and 4.14 m wide. If you made a scale drawing using the scale 1 cm:0.75 m, what would be the dimensions to the nearest tenth?
Holt McDougal Geometry
7-5 Using Proportional Relationships
The rectangular central chamber of the Lincoln Memorial is 74 ft long and 60 ft wide. Make a scale drawing of the floor of the chamber using a scale of 1 in.:20 ft.
Holt McDougal Geometry
7-5 Using Proportional Relationships
Explore dilations further
Characteristics Original Triangle ABC
New Triangle A’B’C’
Observations
Coordinates A(3,5) B(3,2) C(7,2)
Angle Measures 53ᵒ - 90ᵒ - 37ᵒ
Length of Sides
Perimeter
Area
Record observations using a scale factor of 2.
Holt McDougal Geometry
7-5 Using Proportional Relationships
Characteristics Original Rectangle ABCD
New Rectangle A’B’C’D’
Observations
Coordinates A(-2,4), B(-2,-2), C(4,-2), D (4,4)
Angle Measures 90ᵒ - 90ᵒ -90ᵒ - 90ᵒ
Length of Sides
Perimeter
Area
Record observations using a scale factor of 1/2.Explore dilations further
Holt McDougal Geometry
7-5 Using Proportional Relationships
Given that ∆LMN:∆QRT, find the perimeter P and area A of ∆QRS.
Holt McDougal Geometry
7-5 Using Proportional Relationships
∆ABC ~ ∆DEF, BC = 4 mm, and EF = 12 mm. If P = 42 mm and A = 96 mm2 for ∆DEF, find the perimeter and area of ∆ABC.
Holt McDougal Geometry
7-5 Using Proportional Relationships
m AGF=108GF=14, AD=12DG = 4.5, EF = 8AB = 26
1. What is the similarity ratio of ABCD to AEFG?
2. AG 3. DC4. m ADC 5. BC6. Perimeter of ABCD and AEFG7. Ratio of the Perimeters of ABCD to AEFG8. Ratio of the Areas of ABCD to AEFG
Holt McDougal Geometry
7-5 Using Proportional Relationships
Lesson Quiz: Part I
1. Maria is 4 ft 2 in. tall. To find the height of a flagpole, she measured her shadow and the pole’s shadow. What is the height h of the flagpole?
2. A blueprint for Latisha’s bedroom uses a scale of 1 in.:4 ft. Her bedroom on the blueprint is 3 in. long. How long is the actual room?