These are the Theorems you must be familiar with. You DO NOT need to know how to prove these theorems, however ...
You must ...
- Recognise them
- Understand them
- Know how to use them in your geometry problems.
The Completion Level of Your Training.
Theorems you MUST know and Understand
Vertically Opposite Angles are Equal in Measure
In an Isoceles Triangle, Angles Opposite Equal Sides are Equal in Measure
If a Transversal Makes Equal ALternate Angles on two lines, the lines are Parallel
Two Lines are Paralles, if and only if, for any transversal, the corresponding Angles are Equal
The Diagonals of a Parallelogram bisect eachother
If Two Triangles are Similar, then their sides are Proportionate IN ORDER
If Three Parallel Lines cut off equal segments on some transversal, they will cut off equal segments on ALL transversals
In a Triangle ABC a line is drawn parallel to [AB] in a given ratio, it also cuts [AC] in the same ratio
If the Square of one side of a triangle equals the sum of the squares of the other two sides, the angle opposite the first side is 90 degrees
The Tangent to a Circle is at right angles to the radius at the point of contact.