Introduction to Enlargement
Learn what enlargement is and how to enlarge a shape using a scale factor and a centre of enlargement. Let’s get started! 🚀
Video Lesson
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Flashcards
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🛎️ What Is Enlargement?
- Enlargement is a transformation that changes the size of a shape.
- All angles stay the same after an enlargement, but the lengths get bigger or smaller.
🛎️ Understanding the Scale Factor
- The scale factor is the number you multiply all lengths by.
- If the scale factor is greater than 1, the shape gets bigger, and if it is between 0 and 1, the shape gets smaller.
🛎️ How to Enlarge a Shape from a Centre
- Draw straight lines from the centre of enlargement to each corner.
- Measure the distance from the centre to a corner, then mark the new point 3 times as far from the centre.
🛎️ Finding the Centre of Enlargement
- Join each corner of the original shape to the matching corner of the enlarged shape.
- Extend the lines until they meet at one point, called the centre of enlargement.
🛎️ Finding the Scale Factor
- The scale factor is found using .
- If a side goes from 4 units to 8 units, then , so the scale factor is 2.
- Exam tip: Choose any pair of matching sides. Horizontal or vertical lines on the grid are easiest.
Practice Questions
Test your understanding
A square has sides of length . After an enlargement with scale factor 2, what is the length of each side of the new square?
Correct! 🎉 +10 pointsNot quite right
Multiply the original length by the scale factor: . So the new side length is .
If a shape is enlarged by a scale factor between 0 and 1, what happens to its size?
Correct! 🎉 +10 pointsNot quite right
A scale factor between 0 and 1 makes the shape smaller.
The original length of a rectangle is . After enlargement, the length is . What is the scale factor?
Correct! 🎉 +20 pointsNot quite right
Use the formula: scale factor .
A square is enlarged by scale factor 3. The original width is . What is the area after enlargement?
Correct! 🎉 +20 pointsNot quite right
First, find the new width: . Now, area .
On a grid, a rectangle has one corner at . It is enlarged by scale factor 3 from the origin. Where is the matching corner of the new rectangle?
Correct! 🎉 +20 pointsNot quite right
To enlarge from the origin, multiply both numbers in by 3. , . So the new corner is at .
On a grid, a shape has a vertex at . It is enlarged by scale factor 4 from the point . Where is the matching vertex after enlargement?
Correct! 🎉 +30 pointsNot quite right
First, see how far is from the centre . It’s 1 across and 3 up. Multiply both by 4: , . Start at , go 4 across and 12 up. You get . So the new vertex is at .
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Interactive Activity
Learn how to enlarge a shape by a scale factor from a centre of enlargement
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