5.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{b85872d4-00b2-499b-9765-f7559d3de66a-07_953_929_219_422}
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\caption{Figure 3}
\end{figure}
Diagram not drawn to scale
Figure 3 shows the points \(P , Q\) and \(R\).
Points \(P\) and \(Q\) have coordinates ( \(- 1,4\) ) and ( 4,7 ) respectively.
- Find an equation for the straight line passing through points \(P\) and \(Q\).
Give your answer in the form \(a x + b y + c = 0\), where \(a\), \(b\) and \(c\) are integers.
The point \(R\) has coordinates ( \(p , - 3\) ), where \(p\) is a positive constant.
Given that angle \(Q P R = 90 ^ { \circ }\),
- find the value of \(p\).