1) Show $\displaystyle y =\frac{-x^2}{2700}(x-90)$

2) North South distance d-metre between the south semi circle boundary and the cubic model of the wall can be found using:

$\displaystyle d = 19.5-\sqrt{6.25-(x-25)^2} + \frac{x^2}{2700}(x-900)$

a) Domain of $\displaystyle d$ $\displaystyle x$ $\displaystyle \varepsilon [x_{1}, x_{2}]$. Find $\displaystyle x_{1}$ and $\displaystyle x_{2}$

I have attempted these and I am stuck. Any help/hints will be appreciated.