matrices

• shear factor matrix when x axis is invariant

  1 k

  0 1
• shear factor matrix when y axis is invariant

  1 0

  k 1
• unit square

  0 1 1 0

  0 0 1 1
• matrix for rotation of x degrees anticlockwise

  cos x -sin x

  sin x cos x
• for angles between 0-90

  both sin and cos are positive so there is only one negative value in the matrix
• for angles between 90-180

  sin is positive, cos is negative so only bottom left is positive
• for angles between 180-270

  sin and cos are negative so top right value is positive
• for angles between 270-360

  sin is negative, cos is positive so only bottom left is negative
• shear factor

  distance between x coordinate of object / distance of original point from x axis