Geometry Proofs – 6th Year Higher

Synthetic Geometry Proofs:

The following, from are excellent explanations of the Synthetic Geometry Proofs:

Theorem 11: If three parallel lines cut off equal segments on some transversal line, then they will cut off equal segments on any other transversal.

Theorem 12: Let ABC be a triangle. If a line l is parallel to BC and cuts [AB] in the ratio s : t, then it also cuts [AC] in the same ratio.

Theorem 13: If two triangles ABC and  are similar, then their sides are proportional, in order: