4. Find the area of the quadrilateral whose vertices, taken in order, are (– 4, – 2), (– 3, – 5), (3, – 2) and (2, 3).
From the figure:
The coordinates are
Divide the quadrilateral into 2 parts of triangles.
Then the area will be,
Area of the triangle formed by ABC will be,
Area of the triangle formed by ADC will be,
Therefore, the area of the quadrilateral will be:
Alternatively,
The points A and C are in the same ordinates.
Hence, the length of base AC will be
Therefore,
Area of triangle ABC:
Area of triangle ADC:
Therefore, the area will be,