base = x
height = x+6
[tex] \frac{x(x+6)}{2}=56 \\ x(x+6)=56*2 \\ x^2+6x=112 \\ x^2+6x-112=0 \\ x^2+14x-8x-112=0 \\ x(x+14)-8(x+14)=0 \\ (x-8)(x+14)=0 \\ x-8=0 \ \ \ \ \ \ \ or \ \ \ \ \ \ x+14=0\\x=8 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x=-14 \ \ \ \O[/tex]
base = 8 m