How do you enlarge a shape with a sf?

Answer 1

Redraw the same shape with multiplying each length of the shape by the scale factor.

If you are enlarging through a centre of enlargement, measure the distance from each point (vertex) to the centre and continuing on a straight line through the centre, measure that distance multiplied by the scale factor and plot the point there, drawing in the lines of the shape.

When doing this on squared paper, the measurement of the distance can often be easily done by counting the squares horizontally and vertically from the point to the centre, and count each of these values multiplied by the scale factor on the other side of the centre point.

For example, a point (1, 0) enlarged by a scale factor of 2 through the centre (2, 3) would be plotted at:

• Horizontal distance is 2 - 1 = 1 squares, times 2 = 2 squares horizontally beyond (2, 3) which makes the new x co-ordinate 2 + 2 = 4
• Vertical distance is 3 - 0 = 3 squares, times 2 = 6 squares vertically beyond (2, 3) which makes the new y co-ordinate 3 + 6 = 9

Making (1, 0) → (4, 9)