Question

In rectangle ABCD, point A is at (-1,-1) and point B is at (1,2). A diagonal is drawn from point B to point D and it measures 6 units long. Using this information determine the perimeter of the rectangle. Round your answer to the nearest tenth. (1 point)

Answer 1

To determine the perimeter of rectangle ABCD with the given points and conditions, we first need to establish the positions of the points in the rectangle.

Let us denote the points as follows:
- \( A(-1, -1) \) is one vertex.
- \( B(1, 2) \) is the adjacent vertex.
- Let \( C \) be the vertex opposite \( A \) and \( D \) opposite \( B \).

**Finding the Coordinates of Point D:**

Since \( B \) is adjacent to \( A \), we can find point \( D \) using the fact that diagonal \( BD \) measures 6 units.

The distance formula between points \( B(1, 2) \) and \( D(x_D, y_D) \) is given by:
\[
\sqrt{(x_D - 1)^2 + (y_D - 2)^2} = 6
\]

Squaring both sides, we have:
\[
(x_D - 1)^2 + (y_D - 2)^2 = 36
\]

Now, knowing that rectangle ABCD has pairs of opposite sides that are parallel, we can express \( D \) in terms of \( A \). Since \( D \) and \( A \) must have one coordinate of the same sign based on the rectangle characteristics, we can use the symmetry around the center of the rectangle.

Let's denote the coordinates of point \( D \) simply as \( (x_D, y_D) \). The rectangle is symmetric around the midpoints of its sides. Hence, we expect point \( D \) to have its coordinates relating to points \( A \) and \( B \) such that rectangle ABCD can be described with respect to these vertices.

**Finding Midpoint and using Diagonal Property in the Rectangle**:

1. Calculate the midpoint \( M \) of diagonal \( AB \):
\[
M = \left( \frac{-1 + 1}{2}, \frac{-1 + 2}{2} \right) = (0, 0.5)
\]

2. The length of the diagonal of a rectangle is given by:
\[
\text{Length of diagonal} = \sqrt{(x_C - x_A)^2 + (y_C - y_A)^2} = 6
\]
3. Using the distance formula:
\[
6 = \sqrt{(x_D + 1)^2 + (y_D + 1)^2}
\]
Square both sides:
\[
36 = (x_D + 1)^2 + (y_D + 1)^2
\]
At this point, without knowing the exact coordinates of \( D \), we can assume \( D \) will have properties of alignment in the rectangle.

We now need the dimensions of rectangle ABCD. The effective lengths are the projections along the axes defined by the vertices.

**Finding Dimensions:**

Given the coordinates:
1. Length along the x-axis is \( |x_B - x_A| = |1 - (-1)| = 2 \)
2. Height along the y-axis is \( |y_B - y_A| = |2 - (-1)| = 3 \)

The length of the rectangle will also help us define whether it's height falls within limits.

**Calculating the Perimeter:**

The perimeter \( P \) of rectangle ABCD is given by:
\[
P = 2(\text{Length} + \text{Width}) = 2(2 + 3) = 2(5) = 10
\]

Thus, the perimeter of rectangle ABCD is \( \boxed{10.0} \) when rounded to the nearest tenth.