Question

If you wanted to reflect a line segment with one endpoint at (x,y) about the x-axis, which of the following decribes how you might go abput finding the coordinates for the new point after the reflection?

Answer 1

The answer is (x,-y)

Answer 2

You negate the y-coordinate.

Explanation:

A reflection about the x-axis will not change the x-coordinate of any point. This is because it goes straight across the x-axis; this does not change how much left or right of the origin the point is.

However, since each point is reflected across the x-axis, the y-coordinate will change. If it was above the x-axis, it will be below; if it was below the x-axis, it will be above. It will still be the same number of units away from the x-axis, however. This has the effect of negating the y-coordinate.