2TH/vwo §4.2 Calculating with a scale factor

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 2

§4.2 Calculating with a scale factor

First follows a refresh on §4.1 !

§4.2 Calculating with a scale factor

THE SCALE FACTORS HERE ARE:

0.5  AND  3.

A RECAP on RATIO TABLES ...

seems a sensible thing to do now !

In first Form you worked your way through 

a whole paragraph about ratio tables.        

In Ch4 Similarity it suddenly returns...

Let us make start with §4.2 now!

- open your Notebook and 

- open your Textbook, p.130/131

- get a pen, pencil, geo or ruler ready

- we're going to do a Homework exercise together, 

  which saves time to do it yourself, at home  

- WRITE DOWN IN THE MARGIN: 9a        

ANS

Angle ...

1. A
2. B
3. C
4. D

SOLUTION 9a:         B, because the angles are different from A.

Write this in your Notebook!

Now do 9b     

Write down '9b' in the margin and

answer the next slide.

A division for this task could be:

1. 2.5 : 7
2. 4.2 : 1.5
3. 7 : 2.5
4. 1.5 : 4.2

Solution to 9b:   7 : 2.5   and also   4.2 : 1.5

Write this in your Notebook!

Now ..... gets the turn!

What is your answer to 9c?

By the way,  give the scale factor as 

one number!

Let's all write down the Solution in our Notebook:

9c  4.2 : 1.5 = 2.8     or    7 : 2.5 = 2.8

Solutions 9d and 9e:

Homework time 

- make §4.2 Calculating with a scale factor

-  Choose your learning path

-  Make the exercises

-  Check with another colour and with the Solutionsbook

- Take a few pics and send them in in GC

- After this slide the METHOD is shown for making a RATIO TABLE,

  with the final GOAL of calculating an unknown side!