by Brad Simmons
Reflecting a Triangle
Use geometer's sketchpad to reflect a triangle over a line.
Construct the reflected image of triangle ABC over line m.
1. Since point A is on line m, point A is its own reflection. Construct perpendiculars from point B and point C through line m.
2. Locate point Y and point Z so that line m is the perpendicular bisector of segment BY and segment CZ. Points Y and Z are the reflected points of B and C.
3. Hide the construction objects. Connect vertices A, Y, and Z.
Since points A, Y, and Z are reflected images of points A, B, and C, triangle AYZ is the reflection of triangle ABC.
Please click here for a geometer's sketchpad sketch of the figure shown above.