JCHL Geometry 7: Tranformations

Learning work

• Four transformations: translation (slide), central symmetry (point), axial symmetry (fold over a line), rotation (turn)
• Translation: do the SAME move to every point. The image of point C is written C′ (C dash)
• Central symmetry in a point: move each point to the centre and the same distance again (a 180° turn)
• Axial symmetry: fold over the line; in the y-axis only the x-changes sign, in the x-axis only the y-changes sign
• 90° anticlockwise rotation: swap x and y, then change the sign of the new x. Clockwise: swap, then change the sign of the new y