Question

Quadrilateral A B C D has vertices at A negative two comma negative one, B negative four comma negative seven, C negative nine comma negative three and D negative eight comma negative six. It is reflected across the x-axis. What are the new coordinates? Explain.

Answer 1

A reflexion across the x-axis means that every point that was on the x-axis will remain where it was. Every point that was a certain distance below the x-axis will go the same distance above the x-axis. Every point that was a certain distance above the x-axis will go the same distance below the x-axis. The x-coordinate of each point remains the same; the y-coordinate of each point will become its additive inverse. That means that for every point (a, b), the reflection will have coordinates (a, -b).
Examples:
Point (8, 2) becomes (8, -2)
Point (5, 0) remains (5, 0)
Point (3, -7) becomes (3, 7)