Mirror Points
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 4 of 64.
Changing the sign of one coordinate reflects a point across an axis. The new point is called the mirror image of the old one. Start with (3, 2). Changing the sign of y gives (3, -2), which is the mirror image across the x-axis, directly below. Changing the sign of x gives (-3, 2), which is the mirror image across the y-axis. Changing both signs gives (-3, -2), the point on the opposite side of the origin.
Changing one sign reflects the point across one axis
Two points with the same x-coordinate and opposite y-coordinates are reflections of each other across the x-axis. They are the same distance from the x-axis, one above it and one below it.
Challenge
EasyThe 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