If triangle CDE is reflected across y = x, what are the coordinates for the image of triangle C′D′E′?

Solution:
1. Given:
* Reflection line: y = x
* Initial triangle vertices: Let's assume the vertices of triangle CDE are C(x_1, y_1), D(x_2, y_2), and E(x_3, y_3).

2. Reflection Rule across y = x:
* To reflect a point (x, y) over the line y = x, swap the x-coordinate and y-coordinate.

3. Applying the Reflection:
* Vertex C(x_1, y_1) becomes C'(y_1, x_1).
* Vertex D(x_2, y_2) becomes D'(y_2, x_2).
* Vertex E(x_3, y_3) becomes E'(y_3, x_3).