Matrices

• The Identity Matrix

  1 0

  0 1
• Enlargement, scale factor k, about the origin

  k 0

  0 k
• Rotation, 90° clockwise, about the origin

  0 1

  -1 0
• Rotation, 90° anticlockwise, about the origin

  0 -1

  1 0
• Rotation, 180°, about the origin

  -1 0

  0 -1
• Reflection in the x-axis

  1 0

  0 -1
• Reflection in the y-axis

  -1 0

  0 1
• Reflection in the line y=x

  0 1

  1 0
• Reflection in the line y=-x

  0 -1

  -1 0