The sum of the lengths of any two sides of a triangle is greater than the length of the third side.
What is the Triangle Inequality Theorem
If two lines intersect, then their intersection is exactly one point.
What is the Line Intersection Postulate?
The measure of an arc formed by two adjacent arcs is the sum of the measures of the two arcs.
What is the Arc Addition Postulate?
If two planes intersect, then their intersection is a line.
What is the Plane Intersection Postulate?
If three parallel lines intersect two transversals, they divide them proportionally.
What is the Three Parallel Lines Theorem?
In the same circle or congruent circles, two chords are congruent if and only if they are equidistant from the center.
What is the Equidistant Chords Theorem?
For any triangle ABC, where c is the length of the longest side, the following statements are true.
If c^2<a^2+b^2, then triangle ABC is acute.
If c^2>a^2+b^2, then triangle ABC is obtuse.
What is the Pythagorean Inequalities Theorem?
The product of their slopes is -1.
What is the slopes of perpendicular lines?