12.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{aa75f1c1-ee97-4fee-af98-957e6a3fbba1-18_636_887_274_534}
\captionsetup{labelformat=empty}
\caption{Figure 3}
\end{figure}
Figure 3 shows a circle \(C\)
\(C\) touches the \(y\)-axis and has centre at the point ( \(a , 0\) ) where \(a\) is a positive constant.
- Write down an equation for \(C\) in terms of \(a\)
Given that the point \(P ( 4 , - 3 )\) lies on \(C\),
- find the value of \(a\)