In this diagram, the larger rectangle is a scaled copy of the smaller one, and the scale factor is $\frac32$ because $4 \boldcdot \frac32=6$ and $2 \boldcdot \frac32=3$. Scaled copies of rectangles have another interesting property: the diagonal of the large rectangle contains the diagonal of the smaller rectangle. This is the case for any two scaled copies of a rectangle if we line them up as shown. If two rectangles are not scaled copies of one another, then their diagonals would not match up.

A small rectangle inside a larger rectangle with same lower left point and a dashed diagonal line from that lower left point through both upper points. The small rectangle has length 4 and height 2. The large rectangle has length 6 and height 3.