Scale Drawings

Scale Drawings

By Kevvin Hankins

Scale Factors and Scale drawings

Introduction

• What do you notice about the drawing of the horse compared to the actual horse?

• What questions do you have about the two versions?

Scale Drawings

Introduction

• What do you notice about the drawing of the horse compared to the actual horse?

• What questions do you have about the two versions?

Multiple Choice

$$\Delta PQR\ is\ similar\ to\ \Delta STU$$  What side corresponds to side UT?

• PQ

• RQ

• QR

• QP

Multiple Choice

What change was made to the actual horse?

• Exact Copy

• Reduction

• Enlargement

Multiple Choice

Scale Factor is a ratio comparing:

• the new value to the original value

• the original value to the new value

Scale drawing

In order for an original drawing to be reduced or enlarged, every corresponding side must be PROPORTIONAL to the original measurements.

We use MULTIPLICATION to make things bigger or smaller.

Multiple Select

Which pairs of corresponding sides are proportional?

• The bottom of each shape because 4 times 3 is 12

• The right side of each shape because 4 times 3 is 12

• The left side of each shape because 4 times 3 is 12

• The slanted line on the left because 2.2 times 3 is 6.6.

• The slanted line on the right because 2.2 times 3 is 6.6

Multiple Choice

How is Figure F reduced to Figure B?

• Multiply each side by 1/2

• Multiply each side by 1/3

• Multiply each side by 1/4

• Multiply each side by 1/5

Fill in the Blanks

Multiple Choice

Triangle PQR is shown. Its original lengths are multiplied by 2.5. What are the new side lengths of P’Q’R’?

• PQ: 20, RQ: 42.5, RP: 37.5

• PQ: 16, RQ: 34, RP: 30

• PQ:4, RQ:8.5, RP: 7.5

Multiple Choice

Which copies are scale drawings when compared to the original triangle?

• 1, 2, and 3

• 1 and 2

• 2 and 3

• 1

• 2

Multiple Choice

Rectangle ABCD has been enlarged to form rectangle A’B’C’D’. What is the scale factor?

• 2

• 2.5

• 3

• 3.5

Open Ended

Explain why Copy 3 is NOT a scale drawing of the original triangle.

Reminder: You have independent practice

1. Classifying Triangles

2. Intro to Scale Factors

Open Ended

Is Figure B an enlargement of Figure A? Explain why or why not.

Open Ended

Exit Ticket: Triangle PRQ was enlarged to form triangle SUT. What is the scale factor?