When you zoom in on a photo, it becomes larger, but the face is not stretched or flattened. The photo was expanded: everything grew at the same rate.

Enlarge without deforming

PropriedadeThe magnification rule

To enlarge or reduce a figure without deforming:

  • multiply all sides by same number;
  • keep the angles (the corners) the same.

If the number is greater than 1, the figure is enlarged; if it is less than 1, such as ½, it is reduced.

Change the number and compare the yellow figure with the original blue one. Observe what happens to the perimeter and the area.

The area grows faster

Folding the sides of a square of 1 cm, we obtain a square of 2 cm. But inside it fits 4 squares, not 2! The square grew 2 times to the right and 2 times up: 2 × 2 = 4.

Sides multiplied by Perimeter is Area is
2 2 times bigger 4 times bigger
3 3 times bigger 9 times bigger
½ half 4 times smaller
Check the answer

2 m = 200 cm and 3 m = 300 cm. Dividing by 10: 20 cm by 30 cm.

True or false?

  1. When enlarging a figure, the angles remain the same.
  2. If we double the sides of a square, the area also doubles.
  3. A map is a reduction of the region it represents.
  4. To enlarge, just increase the width.