In an ordered pair, the x-coordinate comes first and the y-coordinate comes second. To reflect a point in the x-axis, we use the same x-coordinate and take the opposite of the y-coordinate.
Practice makes perfect
We want to graph the point H(7,8) on the coordinate plane. Then, we want to reflect it across the x-axis.
Graphing the Point
In an ( x, y) ordered pair, the first number tells us the x-coordinate of the point and the second number tells us the y-coordinate of the point. To graph H( 7, 8), we first find 7 on the x-axis and make a mental note of this grid line. The x-coordinate 7 tells us to move 7 units to the right of the origin — the negative horizontal direction.
Next, we find 8 on the y-axis and follow this grid line until it collides with the grid line from our x-coordinate. The y-coordinate 8 tells us to move 8 units up from the origin — the positive vertical direction.
The point H( 7, 8) lies on the point at which these two grid lines intersect.
Graphing the Reflection
We want to reflect a point in the y-axis and then in the x-axis of a coordinate plane. We need to follow two rules to do this.
To reflect a point in the x-axis, we use the same x-coordinate and take the opposite of the y-coordinate.
Let's reflect the given point H(7,8) in the x-axis.
We can see that the point is located at H'(7,-8) after the reflection.
