11 The cross-section of a brick wall built on horizontal ground is given, for \(0 \leq x \leq 6\), by the following function
$$\begin{array} { l l }
0 \leq x \leq 2 & y = 1 \\
2 \leq x \leq 4 & y = - \frac { 1 } { 2 } x ^ { 2 } + 3 x - 3 \\
4 \leq x \leq 6 & y = 1
\end{array}$$
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Units are metres.
- Show that the highest point on the wall is 1.5 metres above the ground.
- Find the area of the cross-section of the wall.