Question 6 (Essay Worth 4 Points)

Triangle [tex]$QRS$[/tex] is drawn with vertices at [tex]$Q(-2, -2)$[/tex], [tex]$R(-6, -6)$[/tex], and [tex]$S(-5, -1)$[/tex]. After a rotation, the image [tex]$Q^{\prime}R^{\prime}S^{\prime}$[/tex] has vertices [tex]$Q^{\prime}(2, -2)$[/tex], [tex]$R^{\prime}(6, -6)$[/tex], and [tex]$S^{\prime}(1, -5)$[/tex].

Part A: Determine the two different rotations that would create the image. (1 point)

Part B: Explain how you know your answer to Part A is correct. (3 points)



Answer :

### Part A: Determine the Two Different Rotations that Would Create the Image

Given two triangles, [tex]\( QRS \)[/tex] with vertices [tex]\( Q(-2, -2), R(-6, -6), S(-5, -1) \)[/tex] and [tex]\( Q'R'S' \)[/tex] with vertices [tex]\( Q'(2, -2), R'(6, -6), S'(1, -5) \)[/tex], we are to determine which rotations could transform [tex]\( QRS \)[/tex] into [tex]\( Q'R'S' \)[/tex].

Rotation by 180 Degrees Around the Origin:
A 180-degree rotation around the origin maps any point [tex]\((x, y)\)[/tex] to [tex]\((-x, -y)\)[/tex].

Let's check if rotating [tex]\( Q'R'S' \)[/tex] 180 degrees back to [tex]\((-x, -y)\)[/tex] yields [tex]\( QRS \)[/tex]:
- [tex]\( Q'(2, -2) \)[/tex] maps to [tex]\((-2, 2) \)[/tex]
- [tex]\( R'(6, -6) \)[/tex] maps to [tex]\((-6, 6) \)[/tex]
- [tex]\( S'(1, -5) \)[/tex] maps to [tex]\((-1, 5) \)[/tex]

These resulting points do not match the original vertices of [tex]\( QRS \)[/tex], so a 180-degree rotation is not a valid transformation.

Rotation by 90 Degrees Clockwise Around the Origin:
A 90-degree clockwise rotation around the origin transforms a point [tex]\((x, y)\)[/tex] to [tex]\((y, -x)\)[/tex].

Let's check if rotating [tex]\( Q'R'S' \)[/tex] 90 degrees back to [tex]\((y, -x)\)[/tex] matches [tex]\( QRS \)[/tex]:
- [tex]\( Q'(2, -2) \)[/tex] maps to [tex]\((-2, -2) \)[/tex]
- [tex]\( R'(6, -6) \)[/tex] maps to [tex]\((-6, -6) \)[/tex]
- [tex]\( S'(1, -5) \)[/tex] maps to [tex]\((-5, -1) \)[/tex]

These resulting points match the original vertices of [tex]\( QRS \)[/tex]. Therefore, a 90-degree clockwise rotation is a valid transformation.

### Part B: Explain How You Know Your Answer is Correct

To verify our solution, we can check the transformations independently:

1. 180-Degree Rotation Check:
- A point [tex]\((x, y)\)[/tex] rotated by 180 degrees around the origin becomes [tex]\((-x, -y)\)[/tex].
- Applying this to [tex]\( Q'(2, -2), R'(6, -6), \)[/tex] and [tex]\( S'(1, -5) \)[/tex] gives [tex]\( (-2, 2), (-6, 6), (-1, 5) \)[/tex] respectively.
- As we can see, these points do not match the vertices of the original triangle [tex]\( QRS \)[/tex], showing that 180 degrees is not a correct rotation.

2. 90-Degree Clockwise Rotation Check:
- A point [tex]\((x, y)\)[/tex] rotated by 90 degrees clockwise around the origin becomes [tex]\((y, -x)\)[/tex].
- Applying this to [tex]\( Q'(2, -2), R'(6, -6), \)[/tex] and [tex]\( S'(1, -5) \)[/tex] gives [tex]\( (-2, -2), (-6, -6), (-5, -1) \)[/tex] respectively.
- These points exactly match the original vertices of [tex]\( QRS \)[/tex].

By confirming that only the transformation involving a rotation of 90 degrees clockwise around the origin results in coordinates that match [tex]\( QRS \)[/tex], we prove that this is the correct rotation. The solution demonstrates methodical application of geometric transformation principles, thus validating the correctness of the identified rotation.