\includegraphics{figure_5}
\includegraphics{figure_6}
A suspension bridge cable \(PQR\) hangs between the tops of two vertical towers, \(AP\) and \(BR\), as shown in Figure 5.
A walkway \(AOB\) runs between the bases of the towers, directly under the cable.
The towers are 100 m apart and each tower is 24 m high.
At the point \(O\), midway between the towers, the cable is 4 m above the walkway.
The points \(P\), \(Q\), \(R\), \(A\), \(O\) and \(B\) are assumed to lie in the same vertical plane and \(AOB\) is assumed to be horizontal.
Figure 6 shows a symmetric quadratic curve \(PQR\) used to model this cable.
Given that \(O\) is the origin,
- find an equation for the curve \(PQR\). [3]
Lee can safely inspect the cable up to a height of 12 m above the walkway.
A defect is reported on the cable at a location 19 m horizontally from one of the towers.
- Determine whether, according to the model, Lee can safely inspect this defect. [2]