Dividing Land

A man leaves a piece of land (see below) to his four sons, with instructions that it should be divided up into 4 equal pieces, each having the same shape as the original piece of land. How can this be achieved?

Source: Julia Robinson Mathematics Festival

SOLUTION
Area of land (trapezoid)
$\frac{1}{2}100\left (100+200\right )=50\left (300\right )$
$=15000 \text{ yds}^2$

Area of each subdivided piece
$15000\div 4=3750 \text{ yds}^2$

Each subdivided piece has the same shape as the original land requires that
$3750=\frac{1}{2}x\left (x+2x\right )$ where $x$ is the length of the smaller base of the new trapezoid.
$2\left (3750\right )=x^2+2x^2$
$7500=3x^2$
$x^2=2500$
$x=\pm 50$
$x=50$ yds

The land is subdivided as shown below