(1)
Remarks
(i)
Since area is a positive quantity, we always take the absolute value of the
determinant in (1) (ii)
If area is given, use both positive and negative values of the determinant for
calculation (iii)
The area of the triangle formed by three collinear points is zero Example 6 Find the area of the triangle whose vertices are (3, 8), (– 4, 2) and (5, 1)