Answer
The quadrilateral QRST is both a square and a rhombus.
Solution
To determine the type of quadrilateral QRST formed by the points \( Q(1, 2) \), \( R(-2, -1) \), \( S(1, -4) \), and \( T(4, -1) \), we will follow these steps:
1. **Calculate the lengths of the sides** to check if it is a rhombus or a square.
2. **Calculate the lengths of the diagonals** to check if it is a rectangle or a square.
3. **Check the properties of the angles** to confirm the type of quadrilateral.
### Step 1: Calculate the lengths of the sides
The distance between two points \( (x_1, y_1) \) and \( (x_2, y_2) \) is given by the formula:
\[
d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}
\]
Let's calculate the lengths of the sides \( QR \), \( RS \), \( ST \), and \( TQ \).
- **Length of \( QR \)**:
\[
d_{QR} = \sqrt{((-2) - 1)^2 + ((-1) - 2)^2} = \sqrt{(-3)^2 + (-3)^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2}
\]
- **Length of \( RS \)**:
\[
d_{RS} = \sqrt{(1 - (-2))^2 + ((-4) - (-1))^2} = \sqrt{(3)^2 + (-3)^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2}
\]
- **Length of \( ST \)**:
\[
d_{ST} = \sqrt{(4 - 1)^2 + ((-1) - (-4))^2} = \sqrt{(3)^2 + (3)^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2}
\]
- **Length of \( TQ \)**:
\[
d_{TQ} = \sqrt{(1 - 4)^2 + (2 - (-1))^2} = \sqrt{(-3)^2 + (3)^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2}
\]
### Step 2: Calculate the lengths of the diagonals
Now, let's calculate the lengths of the diagonals \( QS \) and \( RT \).
- **Length of \( QS \)**:
\[
d_{QS} = \sqrt{(1 - 1)^2 + (2 - (-4))^2} = \sqrt{(0)^2 + (6)^2} = \sqrt{36} = 6
\]
- **Length of \( RT \)**:
\[
d_{RT} = \sqrt{(4 - (-2))^2 + ((-1) - (-1))^2} = \sqrt{(6)^2 + (0)^2} = \sqrt{36} = 6
\]
### Step 3: Analyze the properties
- All sides are equal: \( QR = RS = ST = TQ = 3\sqrt{2} \) (indicating it could be a rhombus or square).
- The diagonals are equal: \( QS = RT = 6 \) (indicating it could be a rectangle or square).
### Conclusion
Since all sides are equal and the diagonals are equal, the quadrilateral QRST is a **square**. It is also a **rhombus** because all sides are equal.
Thus, the correct options are:
- b. square
- c. rhombus
The final answer is:
- **b. square**
- **c. rhombus**
Answered by UpStudy AI and reviewed by a Professional Tutor
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