4 The coordinates of the points \(\mathrm { A } , \mathrm { B }\) and C are ( \(- 2,2\) ), ( 1,3 ) and ( \(3 , - 3\) ) respectively.
- Find the gradients of the lines AB and BC .
- Show that the triangle ABC is a right-angled triangle.
- Find the area of the triangle ABC .