10 A triangle has vertices \(A ( 1,4 ) , B ( 7,0 )\) and \(C ( - 4 , - 1 )\).
- Show that the equation of the line AC is \(\mathrm { y } = \mathrm { x } + 3\).
M is the midpoint of AB . The line AC intersects the \(x\)-axis at D .
- Determine the angle DMA.