<h2>

**Explanation:**</h2>

In every **rectangle, **the two diagonals have the same length. If a quadrilateral's diagonals have the same length, that doesn't mean it has to be a rectangle, but if a parallelogram's diagonals have the same length, then it's definitely a rectangle.

So first of all, let's prove this is a parallelogram. The basic **definition of a parallelogram** is that it is a quadrilateral where both pairs of opposite sides are parallel.

So let's name the vertices as:

**First pair of opposite sides:**

<u>Slope:</u>

**Second pair of opposite sides:**

<u>Slope:</u>

So in fact this is a parallelogram. The other thing we need to prove is that the diagonals measure the same. Using **distance formula:**

So the diagonals measure the same, therefore** this is a rectangle.**

15/7 is approximately 2.143

**Answer:**

x = -7

**Step-by-step explanation:**

- 23 = 5 + 4x

- 5 = - 5

- 28 = 4x

/4 = /4

- 7 = x