The points [tex]\(A(-3,4), B(3,2), C(1,-4),\)[/tex] and [tex]\(D(-5,-2)\)[/tex] form quadrilateral [tex]\(ABCD\)[/tex] on the coordinate plane. What condition verifies that the diagonals are perpendicular?

A. The diagonals have the same length.
B. The product of the slopes of the diagonals is 1.
C. The diagonals have different lengths.
D. The product of the slopes of the diagonals is -1.



Answer :

To determine which condition verifies that the diagonals of quadrilateral [tex]\(ABCD\)[/tex] are perpendicular, we need to examine the slopes of the diagonals [tex]\(AC\)[/tex] and [tex]\(BD\)[/tex]. Here, we will find the respective slopes first and then analyze the product of those slopes.

1. Identifying the Points:
- [tex]\(A(-3, 4)\)[/tex]
- [tex]\(C(1, -4)\)[/tex]
- [tex]\(B(3, 2)\)[/tex]
- [tex]\(D(-5, -2)\)[/tex]

2. Calculating the Slope of Diagonal [tex]\(AC\)[/tex]:
The slope [tex]\(m_{AC}\)[/tex] of a line passing through two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is given by:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]
For points [tex]\(A(-3, 4)\)[/tex] and [tex]\(C(1, -4)\)[/tex]:
[tex]\[ m_{AC} = \frac{-4 - 4}{1 + 3} = \frac{-8}{4} = -2 \][/tex]

3. Calculating the Slope of Diagonal [tex]\(BD\)[/tex]:
For points [tex]\(B(3, 2)\)[/tex] and [tex]\(D(-5, -2)\)[/tex]:
[tex]\[ m_{BD} = \frac{-2 - 2}{-5 - 3} = \frac{-4}{-8} = \frac{1}{2} = 0.5 \][/tex]

4. Calculating the Product of Slopes:
To verify if the diagonals are perpendicular, we check the product of the slopes:
[tex]\[ m_{AC} \times m_{BD} = -2 \times 0.5 = -1 \][/tex]

5. Conclusion:
The product of the slopes of the diagonals is [tex]\(-1\)[/tex]. When the product of the slopes of two lines is [tex]\(-1\)[/tex], it means that the lines are perpendicular. Therefore, the condition that verifies the diagonals of quadrilateral [tex]\(ABCD\)[/tex] are perpendicular is that the product of the slopes of the diagonals is [tex]\(-1\)[/tex].

Thus, the correct answer is:
[tex]\[ \boxed{\text{D. The product of the slopes of the diagonals is -1.}} \][/tex]

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