Congruent plane figures, superimposition proofs of congruence, plane isometries (superimposing the plane onto itself), symmetries Congruent segments and angles; addition/subtraction of segments and angles; supplementary angles, vertical angles broken lines, polygons, triangles axiom: there is a unique line thru any two distinct points; corollaries existence and uniqueness of a perpendicular to a given line thru a given point isosceles triangle, properties congruence tests for triangles exterior angles; inequalities between angles and sides in a triangles (the greater side is opposite the greater angle, etc) the triangle inequality, its generalization to broken lines right triangles; theorems on lengths of perpendicular and slants segment and angle bisectors as geometric loci; all three perp bisectors in a triangle intresect at one point, and similarly for angle bisectors tests for parallel lines (corresponding angles etc) the parallel postulate, corollaries sum of angles in a triangle, in convex polygons parallelograms, rectangles, rhombi, trapezoids, their properties and testing for them circles central and inscribed angles chords and their properties tangent lines inscribed/circumscribed triangles, quadrilaterals construction problems based on all of the above