Affine plane coordinates

Affine coordinate relative to a point A and a baseline BC

Definition as relative A-height

Ways to compute coordinate of a point P

Parallel lines and parallelograms

Transversals

Special case of a lattice

How to plot a point (ambiguous case is a locus)

Affine Coordinates with respect to two intersecting axes

How to measure coordinates

How to plot a point

Equation of a line

Trilinear or Barycentric coordinates with respect to a triangle

Three affine coordinates of a point P defined by triangle

Sum of 3 coordinates = 1

Coordinates and areas cut by parallels through P

Ratios on sides and on cevian lines through P

Special case of lattices and subdivisions of triangle

Ceva's theorem and Menelaus theorem

Relation to center of mass