For minimum perimeter, the vertex angle must be 90°

$A = \frac{1}{2}(2h)(h) = h^2$

$P = 2\sqrt{2}h$

$R = \dfrac{A}{P} = \dfrac{h^2}{2\sqrt{2}h} = \dfrac{\sqrt{2}}{4}h$

$Q = A \dfrac{1}{n}R^{2/3} S^{1/2}$

$0.7 = h^2 \dfrac{1}{0.012}(\frac{1}{4}\sqrt{2}h)^{2/3}(0.0001^{1/2})$

$h = 1.215 ~ \text{m}$ ← *answer*