Math Textbook: 2.2 #26

26. Four points, A, B, C, and D, have the following co-ordinates:
A(0.75, 0.81)
B(0.75, -0.65)
C(-1.22, -0.65)
D(-1.22, 0.81)

What is the area of quadrilateral ABCD, to the nearest hundreth of a square unit?

--- What I did ---

Step 1: In my head, I imagined and took a guess on where the co-ordinates would show up on a co-ordinate grid.

Step 2: I then had to determine the length between A and B, using the x-axis co-ordinates. The co-ordinates for A and B are 0.81 and (-0.65). To find the difference between those 2 numbers, you would need to subtract.

The difference between 0.81 and (-0.65) is 1.46. So, the length between x-axis co-ordinates A and B is 1.46 units.

Step 3: I then had to find the length between A and D, using the y-axis co-ordinates. The co-ordinates for A and D are 0.75 and (-1.22). To find the difference between those 2 numbers, you would need to subtract.

The difference between 0.75 and (-1.22) is 1.97. So, the length between x-axis co-ordinates A and D is 1.97 units.

Step 4: You need to find the area of ABCD. To find the area of quadrilateral ABCD to the nearest hundreth of a square unit, you use the formula length x width.

The area of quadrilateral ABCD to the nearest hundreth of a square unit is 2.88u2.