Question

Which figure represents the image of parallelogram LMNP after a reflection across the line y = x?

A.figure A
B.figure B
C.figure C
D.figure D

NOT D

Answer 1

A reflection across the line y = x has a rule:

(x,y)→(y,x).

Parallelogram LMNP has vertices L(3,1), M(4,3), N(5,3) and P(4,1).

Then

• L(3,1)→L'(1,3)
• M(4,3)→M'(3,4)
• N(5,3)→N'(3,5)
• P(4,1)→P'(1,4)

Points L', M', N' and P' are exactly vertices of figure C.

Answer: correct choice is C.

Answer 2

the answer is C
first draw line y=x that's simply line that increases from left to right and has slope of one and goes thru origin.
you now see its reflected