Enlargement and area

Enlargement and area

Pencil and paper
Overview
Connecting to the Curriculum
Marking Student Responses
Further Resources
This task is about enlarging a shape on a grid and exploring the relationship between scale factor and area.

          
 

a) What is the area of the triangle ABC? _________ square units
 
b) 		  
Using P as the centre of enlargement, enlarge the triangle ABC by a scale factor of 3. Label the enlarged triangle A', B', and C' respectively.
 
c)		  
What is the area of the triangle A'B'C'? _________ square units
 
d)
  
If the triangle ABC is enlarged by a scale factor of 4, how could you find the area of the enlarged triangle without drawing it?
 
 

 

 
Level:
5
Curriculum info: 
Maths, Geometry and Measurement, Measurement, Transformation
Keywords: 
enlargement, resizing, scale factor, area
Description of task: 
Students enlarge a shape on a grid and explore the relationship between scale factor and area.
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Geometric thinking, set 6
Measurement sense, sets 7-8
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y10 (09/1998)
a) 1 moderate
b) Triangle A'B'C' correctly drawn as below
[the dotted lines are not required.]

 difficult
c) 9 difficult
e) Any 1 of:

  • Multiply the area of triangle ABC by 16.
  • Multiply the area of triangle ABC by 42.
  • Multiply the area of triangle ABC by the scale factor squared.
 very difficult