How do you make a math enlargment?

Answer 1

An enlargement is usually described by a scale factor, f, AND a centre of enlargement, O. For simplicity, I will refer to the original shape or the pre-image as A, and the image, after enlargement, as B.

Take any point P, on A. Join OP. Multiply the distance OP by f. Extend the line OP to OQ so that its length is which OP*f. Then Q is the image of P. In principle, you need to repeat this for every point on the shape A. However, if A is a shape made up of straight lines (a polygon in 2d or polyhedron on 3d) , you need only find the images of its vertices and join them up with straight lines in the same order. Unfortunately, this does not work with curved shapes.

In mathematical terms, "enlargement" can also mean shrinking. If the scale factor f is between 0 and 1, the image will be smaller than the pre-image.

Also, if f is negative, then the image will be an inverted image on the other side of O. Again, the image will be smaller than the pre-image if the absolute value of f is less than 1 (ie -1< f <0) and larger than the pre-image if f<-1.