1. A What is the ratio of Area to Width of rectangle A? A W 4 u 20 u2= 5 A 10 15 20
5 units
20 u2
4 units
Lesson 1 TD 3
Determine the area of rectangle A. A
5u x 4u =
20 u2
NCSC – Mathematics Lesson 2

2. A A A B 5 units 5 units 8 units 4 units A 20 u2 W 4 u = =10 15 20 A B A
5 units
5 units
4 units
8 units
Lesson 1 TD 3
What happens to the area of rectangle A if we double the width?
If the ratio of Area to Width of rectangle A is
A u2
W u =
Use the ratio to figure the Area of rectangle B?
A A
W W = B A
NCSC – Mathematics Lesson 2

3. 1 2 A B B 5 units 5 units 8 units 5 units = = A A W W B A10 15 20 1 25 5 B B 10 15 20 2 30 35 40
5 units
5 units
8 units
5 units
Lesson 1 TD 3
A A
W W = B A
Use ratios and proportions to find the Area of rectangle B?
What do we need to do to the area in the proportion?
Check your answer by counting the units within rectangle B.
What did we do to the width of rectangle A to get rectangle B x2
40 u2
20 u A
4 u u = B A x2
NCSC – Mathematics Lesson 2

4. 1 A 2 C 10 units 5 units 4 units 4 units = = A A L L B A20 30 40
10 units 5 10 20 A 15 2
5 units
Lesson 1 TD 3
4 units
4 units
A A
L L = B A
Use ratios and proportions to find the Area of rectangle B?
Check your answer by counting the units within rectangle B.
What do we need to do to the area in the proportion?
What did we do to the length of rectangle A to get rectangle B x2
40 u2
20 u A
5 u u = B A x2
NCSC – Mathematics Lesson 2