Khan Academy

Triangle congruence review (K-A)

Why SSA isn't a congruence postulate/criterion (K-A)

Angles in a triangle sum to 180° proof (K-A)

Proofs concerning equilateral triangles (K-A)

Proofs concerning isosceles triangles (K-A)

Corresponding angles in congruent triangles (K-A)

Finding angles in isosceles triangles (example 2) (K-A)

Finding angles in isosceles triangles (K-A)

Isosceles & equilateral triangles problems (K-A)

Proof: Diagonals of a parallelogram (K-A)

Proof: Opposite angles of a parallelogram (K-A)

Proof: Opposite sides of a parallelogram (K-A)

Proof: Rhombus area (K-A)

Proof: Rhombus diagonals are perpendicular bisectors (K-A)

Proof: The diagonals of a kite are perpendicular (K-A)

Geometry proof problem: congruent segments (K-A)

Geometry proof problem: midpoint (K-A)

Geometry proof problem: squared circle (K-A)

Geometric constructions: angle bisector (K-A)

Geometric constructions: perpendicular bisector (K-A)

Geometric constructions: perpendicular line (K-A)

Euclid as the father of geometry (K-A)

Geometric definitions example (K-A)

Lines, line segments, & rays (K-A)

Specifying planes in three dimensions (K-A)