Mirror Points
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 4 of 64.
Flipping one sign reflects a point across an axis. From (3, 2), changing the y gives (3, -2): the mirror image across the x-axis, straight below. Changing the x gives (-3, 2): the mirror across the y-axis. Changing both gives (-3, -2), the point on the far side of the origin.
One sign flip, one reflection
The rule is worth saying backwards too: two points that differ only in the sign of y sit at the same height mirrored over the x-axis, and the axis is exactly halfway between them.
Challenge
The point (-4, 3) is drawn. Place its reflection across the x-axis.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Graphs & Systems
1The Coordinate Plane
Two Numbers, One PointThe Four QuadrantsPoints on the AxesMirror PointsRecap: The Plane4Slope-Intercept Form
y = mx + bThe Starting HeightWrite the EquationSolve for yDraw From Any FormRecap: y = mx + b7Parallel & Perpendicular
Same Slope, Never MeetThe Perpendicular SlopeA Right-Angle LineRecap: Two Relations2From Rule to Line
A Rule Makes PointsThe Points Line UpOn the Line or Not?Between the DotsRecap: Rule to Line