Reflection Across the Y Axis
A y axis reflection is a horizontal flip. Every point moves to the opposite side of the vertical axis. The height stays unchanged. The distance from the axis also stays unchanged. This makes the rule simple, but it is still useful in geometry, design, mapping, and coordinate checks.
What the Calculator Does
This calculator handles single points, many points, polygon vertices, and line equations. It changes each x value to its opposite sign. It keeps each y value the same. It also shows the ordered pair rule, distance from the y axis, and quadrant changes. When polygon mode is used, it keeps area and perimeter for comparison.
Why the Rule Works
The y axis is the mirror line. Any point on this line has an x value of zero. A point to the right has a positive x value. A point to the left has a negative x value. Reflection swaps these positions. The point does not move up or down. Only the horizontal direction changes.
Working With Shapes
A shape can be reflected by transforming every vertex. Join the new vertices in the same order. The reflected shape has the same size. Its orientation is reversed. This is useful when checking symmetry or preparing mirrored parts. Designers can use it before drawing a second half of a plan.
Line Equation Support
The calculator can also reflect a line written as Ax + By + C = 0. Under a y axis reflection, x is replaced by -x. This changes A to -A. B and C remain the same. The resulting equation describes the mirror image of the original line.
Practical Uses
Students can verify homework steps quickly. Teachers can create examples with exported reports. Engineers can mirror simple coordinate layouts. Builders can check symmetrical drawings. The CSV file helps with spreadsheets. The PDF file helps with sharing a clean result sheet.
Accuracy Tips
Use decimal precision that matches your task. Enter points in clear pairs. Keep polygon vertices in order. Avoid mixing commas and spaces in confusing ways. Review the table before exporting. Use notes for repeated checks. A reflected point should always have the same y value. Its x value should always have the opposite sign.