Question

If ABC is reflected across the y-axis, what are the coordinates of C?

A. (6,-3)
B. (3,-6)
C. (-6,-3)
D. (-6,3)

Answer 1

D (-6, 3)

Explanation:

the point C is originally (6, 3).

that means the x coordinate is 6, the y coordinate is 3.

now, if we reflect (= mirror) that point across the y axis, that means we mirror it to the other side of the y axis.

the y axis is the vertical coordinate axis in the middle of the graph.

so, what is going to happen to the point ?

will the y coordinate change ? no. the point will move over to the other side of the y line in the same "height" as before. nothing will move it higher or lower.

so, it will keep the same y coordinate : 3.

will the x coordinate change ? oh, yes. because the point will move from the right of the y axis to the left of the y axis. and it will be the same distance to the left as it was originally to the right.

so, +6 turns into -6 (as the y axis represents x=0).

Answer 2

Explanation:

The correct answer would be C (-6,3). The y axis is the bold line going up and down on the middle of the page. If you were able to pick up triangle and flip it over the y axis. Point C would land at (-6,3).

Also, you can see that point C is six spaces to the right of the y axis. That means when we flipped it over the axis, it will now be six paces to the right of the y axis. Since the point did not go up or down when you flipped it. It is still 3 spaces above the x axis.