7. (a) The line \(L _ { 1 }\) passes through the points \(A ( - 3,0 )\) and \(B ( 1,4 )\). Determine the equation of \(L _ { 1 }\).
(b) The line \(L _ { 2 }\) has equation \(y = 3 x - 3\).
- Given that \(L _ { 1 }\) and \(L _ { 2 }\) intersect at the point \(C\), find the coordinates of \(C\).
- The line \(L _ { 2 }\) crosses the \(x\)-axis at the point \(D\). Show that the coordinates of \(D\) are \(( 1,0 )\).
(c) Calculate the area of triangle \(A C D\).
(d) Determine the angle \(A C D\).