Question

Which of those would be a coordinate of the image of triangle ABC after it is reflected across the line y=x?

Answer 1

It would be answer B because when you are given y=x all you do at that point is flop the spot of the x and the y so when you do that is will turn into

A (-1,3)--- A' (3,-1)

B(2,4)---- B' (4,2) answer

C (1,2)---- C' (2,1)