Do Now 1/17/12Do Now 1/17/12 Take out HW from Friday.Take out HW from Friday.

Practice worksheets 4.5 B & CPractice worksheets 4.5 B & C

Copy HW in your planner.Copy HW in your planner. Text p. 174, #1-12 all, 15, 16, 19, & 20 Measurements of your bedroom (length & width) and at least 4 objects (bed,

dresser, desk, etc…) Quiz sections 4.4 – 4.6 Friday Chapter 4 Test Tuesday 1/24

Be ready to copy POTW #7Be ready to copy POTW #7

Homework Practice worksheet 4.5 B & C

1) 60 cm 2) 44° 3) 21° 4) 12 in 5) 2.8 ft 6) 16.5 ft

1) 21.6 yd 2) 56° 3) 26° 4) 22.1 m 5) 9.5 meters 6) 28 feet 7) 225 inches 8) 112 feet

Objective

SWBAT understand ratios and proportions in scale drawings and use ratios and proportions with scale

Section 4.6 “Scale Drawings and Section 4.6 “Scale Drawings and Scale Models”Scale Models”

SCALE DRAWING-SCALE DRAWING-A proportional two-dimensional A proportional two-dimensional drawing of an object. Its drawing of an object. Its dimensions are related to the dimensions are related to the dimensions of the actual object dimensions of the actual object by a ratio called the by a ratio called the SCALE SCALE FACTOR.FACTOR.

Identify the scale factor. Identify the scale factor.

13.5108Width (in.)

18144Length (in.)

BlueprintRoom blueprint lengthroom length

= 18

18144

=

A scale factor is always the ratio of the model’s dimensions to the actual object’s dimensions.

Caution!

318Wing span (in.)

212Length (in.)

BlueprintModel Aircraft

blueprint length aircraft length

=2

12

=16

SCALESCALE - - the SCALE of a drawing, map, or model relates the the SCALE of a drawing, map, or model relates the dimensions of the drawing, map, or model to the actual dimensions of the drawing, map, or model to the actual dimensions.dimensions.

Write and solve a proportion to find Write and solve a proportion to find the distance the distance dd between Cleveland and between Cleveland and Cincinnati if the distance on the map Cincinnati if the distance on the map is about 4.2 centimeters.is about 4.2 centimeters.

==4.24.2 dd

11 centimeterscentimeters8585 kilometerskilometers

Cross products propertyCross products property

d d = 357= 357 Simplify.Simplify.

1 1 d d = 85 4.2= 85 4.2

SCALE MODEL-SCALE MODEL-A proportional three-dimensional A proportional three-dimensional model of an object. model of an object.

A dinosaur model kits sold at a hobby store has A dinosaur model kits sold at a hobby store has a scale of a scale of 1 ft : 25 ft.1 ft : 25 ft. A completed model of the A completed model of the dinosaur is dinosaur is 1.61.6 feet long. Estimate the actual feet long. Estimate the actual length of the dinosaur. length of the dinosaur.

Write and solve a proportion to find Write and solve a proportion to find the length the length gg of the dinosaurof the dinosaur..

==1.61.6 gg

112525

Cross products propertyCross products property

g g = 40= 40 Simplify.Simplify.

1 1 ∙∙ g g = 25 = 25 ∙∙ 1.6 1.6

SOLUTIONSOLUTION

The actual length of the dinosaur is about 40 feet.The actual length of the dinosaur is about 40 feet.

A model of a space shuttle has a scale of A model of a space shuttle has a scale of 1 : 52.1 : 52. The space shuttle has a wingspan of 78 feet. The space shuttle has a wingspan of 78 feet. Find the model’s wingspan. Find the model’s wingspan.

Write and solve a proportion to find Write and solve a proportion to find the wingspan the wingspan ww of the space shuttleof the space shuttle..

== ww 7878

115252

Cross products propertyCross products property

1.51.5 = w= w Simplify.Simplify.

1 1 ∙∙ 78 78 = 52 = 52 ∙∙ w w

SOLUTIONSOLUTION

The wingspan of the model is 1.5 feet.The wingspan of the model is 1.5 feet.

A scale drawing of a basketball court has a scale of 1 inch : 9 feet.

The basketball court is 94 ft by 50 ft. Find the The basketball court is 94 ft by 50 ft. Find the dimensions of the court in the scale drawing. dimensions of the court in the scale drawing.

ft

in

9

1

ft

inL

94

ft

in

9

1

ft

inW

50

L L = 10 4/9in= 10 4/9in

1 1 ∙∙ 94 94 = 9 = 9 · L· L

W W = 5 5/9in= 5 5/9in

1 1 ∙∙ 50 50 = 9 = 9 ∙∙ W W

A scale drawing of a basketball court has a scale of 1 inch : 9 feet.

The free throw line is 15 feet from the The free throw line is 15 feet from the backboard. How far is it in the scale backboard. How far is it in the scale drawing?drawing?

ft

in

9

1

ft

inb

15 b b = 1 2/3in= 1 2/3in

1 1 ∙∙ 15 15 = 9 = 9 · b· b

Homework

Text p. 174, #1-12 all, 15, 16, 19, & 20

NJASK7 Prep