Find the area of a trapezoid whose vertices have coordinates (4; 2) (9; 2) (9; 8) (1; 8)

Let’s analyze these points, the coordinates of which are given, from the position of belonging to their bases of the trapezoid:

Points with coordinates (4; 2) and (9; 2) belong to the lower base, since their ordinates are equal to each other 2 = 2. The length of the base is a = 9 – 4 = 5.

Points with coordinates (9; 8 and (1; 8) are the upper base with ordinates 8 = 8. Length in = (9 – 1) = 8.

Height n = the difference between the ordinates of the upper and lower points: n = (8 – 2) = 6.

All data for area C found:

C = (a + b) * n / 2 = (5 + 8) * 6/2 = 13 * 3 = 39 (square units).