Sumy is working in geometry class and is given figure ABCD in the coordinate plane to reflect. The coordinates of point D are (a, b). She reflects the figure over the line y = x.

What are the coordinates of the image D'?

A. (a, -b)
B. (b, a)
C. (-a, b)
D. (-b, -a)



Answer :

Let's analyze the problem step by step:

1. Understanding Reflection Over the Line [tex]\(y = x\)[/tex]:
- When reflecting a point over the line [tex]\(y = x\)[/tex], the x-coordinates and y-coordinates of the point swap places.
- That is, for any point [tex]\((x, y)\)[/tex], its reflection over [tex]\(y = x\)[/tex] will be [tex]\((y, x)\)[/tex].

2. Identifying the Coordinates of Point [tex]\(D\)[/tex]:
- The given coordinates for point [tex]\(D\)[/tex] are [tex]\((a, b)\)[/tex].

3. Finding the New Coordinates After Reflection:
- According to the reflection rule, to find the new coordinates of the reflected point [tex]\(D^{\prime}\)[/tex], we swap [tex]\(a\)[/tex] (the x-coordinate) and [tex]\(b\)[/tex] (the y-coordinate).
- So, the coordinates of point [tex]\(D^{\prime}\)[/tex], the image after reflection, will be [tex]\((b, a)\)[/tex].

4. Choosing the Correct Option:
- We find that the correct coordinates of the image [tex]\(D^{\prime}\)[/tex] are [tex]\((b, a)\)[/tex].

Thus, the coordinates of the image [tex]\(D^{\prime}\)[/tex] after reflecting over the line [tex]\(y = x\)[/tex] are:
[tex]\[ \boxed{(b, a)} \][/tex]