SAT Study Guide/Part 2 - The Math Section/Concepts from Geometry

The SAT generally does not test any arcane or difficult geometry; however, it is important to know several rules.

Degrees and Angles

 * 1)  A circle contains 360 degrees. Every circle contains 360 degrees. Each degree is 1/360 of the total distance around the outside of the circle.
 * 2)  A line is a 180-degree angle. A line is a flat angle. Half a circle, or a semicircle, is also a 180 degree angle.
 * 3)  When two lines intersect, four angles are formed.
 * 4)  If two lines are perpendicular, their slopes are negative reciprocals.  If line A has a slope of 3, and line B is perpendicular to A, it has a slope of -1/3.
 * 5)  When two lines intersect, the angles opposite each other will have the same measures.  These are known as vertical angles.  The total of all four angles created is 360 degrees.
 * 6)  The sum of the lengths of any two sides of a triangle must be larger than the length of the remaining side.
 * 7)  A rectangle + two triangles on opposite sides = a trapezoid.