A field is shaped like a trapezium whose parallel sides are 77 $m$ and 60 $m$, while its slant sides measure 26 $m$ and 25 $m$. Find its area in $m^2$.

The two foot-pieces $x$ (under the 25 m side) and $y$ (under the 26 m side) satisfy $x+y=77-60=17$ and $25^2-x^2=26^2-y^2$, so $y^2-x^2=51$ and $y-x=3$. Hence $y=10$ and $x=7$, and the height = √(625 − 49) = √576 = 24 m. Area = ½ × $(77+60)\times 24$ = ½ × $137\times 24=1644{\text{m}}^2$.