If x = height and y = base, Area = x * y
y = x + 10
x * (x + 10) = Area
x^2 + 10x = 24
x^2 + 10x - 24 = 0
(x + 12)(x - 2) = 0
x = -12 (impossible, a measurement of width/length cannot be negative, so we cancel this solution out) or x = 2.
The answer is 2cm.