Complementary and Supplementary Angles
Basics of complementary, supplementary, adjacent and straight angles. Also touching on what it means to be perpendicular

Other Triangle Congruence Postulates
SSS, SAS, ASA and AAS postulates for congruent triangles. Showing AAA is only good for similarity and SSA is good for neither

Equilateral and Isosceles Example Problems
Three example problems involving isosceles and equilateral triangles. 2 from Art of Problem Solving (by Richard Ruscyk) book

Area of Inscribed Equilateral Triangle (some basic trig used)
Problem that requires us to figure out the area of an equilateral triangle inscribed in a circle (A little trigonometry used)

Circumcenter of a Triangle
Multiple proofs showing that a point is on a perpendicular bisector of a segment if and only if it is equidistant from the endpoints. Using this to establish the circumcenter, circumradius, and circumcircle for a triangle

Three Points Defining a Circle
Showing that three points uniquely define a circle and that the center of a circle is the circumcenter for any triangle that the circle is circumscribed about

Point Line Distance and Angle Bisectors
Thinking about the distance between a point and a line. Proof that a point on an angle bisector is equidistant to the sides of the angle and a point equidistant to the sides is on an angle bisector

Medians divide into smaller triangles of equal area
Showing that the three medians of a triangle divide it into six smaller triangles of equal area. Brief discussion of the centroid as well

Proving that the Centroid is 2-3rds along the Median
Showing that the centroid divides each median into segments with a 2:1 ratio (or that the centroid is 2/3 along the median)

Proof - Triangle Altitudes are Concurrent (Orthocenter)
Showing that any triangle can be the medial triangle for some larger triangle. Using this to show that the altitudes of a triangle are concurrent (at the orthocenter).

Proof - Rhombus Area Half Product of Diagonal Length
Showing that we can find the area of a rhombus by taking half the product of the lengths of the diagonals

Area of a Regular Hexagon
Using what we know about triangles to find the area of a regular hexagon

Geometry

Source of these courses is khan
Videos on geometry. Basic understanding of Algebra I necessary. After this, you'll be ready for Trigonometry.
khan
Website: http://www.dnatube.com/school/khan