Through any two points there is exactly one line.
Through any three noncollinear points there is exactly one plane containing them.
If two points lie in a plane, then the line containing those points lies in the plane.
If two lines intersect, then they intersect in exactly one point.
If two planes intersect, then they intersect in exactly one line.
The points on a line can be put into a one-to-one correspondence with the real numbers.
Segment Addition Postulate
If B is between A and C, then AB + BC = AC.
Given line AB and a point O on line AB, all rays that can be drawn from O can be put into a one-to-one correspondence with the real numbers from 0 to 180.
Angle Addition Postulate
If S is in the interior of <PQR, then m< PQS + m∠< SQR = m<PQR
In a right triangle, the sum of the squares of the lengths of the legs is equal to the square of the length of the hypotenuse.