Question

How do you know which triangle is the original and which is the dilation?

Answer 1

$\green {\text{How do you tell if a figure is a dilation?}}$

A description of a dilation includes the scale factor (or ratio) and the center of the dilation. The center of dilation is a fixed point in the plane. If the scale factor is greater than 1, the image is an enlargement (a stretch). If the scale factor is between 0 and 1, the image is a reduction (a shrink).