are coplanar lines that do not intersect
are non coplanar lines. There forth, they are are neither parallel nor intersecting.
If two parallel planes are cut by a third plane, then the lines of intersection are parallel
is a line that intersects two or more coplanar lines in different points.
Alternate interior angles
are two nonadjacent interior angles on oposite sides of the transversal.
Same-Side interior angles
are two interior angles on the same side of the transversal.
are two angles in corresponding postions relative to the two lines
If two parallel lines are cut by a transversal, then the corresponding angles are congruent.
if two lines are cut by a transversal, then alternate interior angles are congruent.
If two parallel lines are cut by a transversal, then same-side interior angles are supplementary.
If a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other one also.
If two lines are cut by a transversal and corresponding angles are congruent, then the lines are parallel.
If two lines are cut by a transversal and alternative interior angles are congruent, then the lines are parallel.
If two lines are cut by transversal same side interior angles are supplementary, then the lines are parallel
In a plane two lines are perpendicular to the same line are parallel.
Through a point outside a line, there is exactly one line parallel to the given line.
Through a point outside a line, there is exactly one line perpendicular to the given point.
Two lines parallel to a third line are parallel to each other
is a figure formed by three segments joining three non collinear points
The sum of the measures of the angles of a triangle is 180
If two angles of one triangle are congruent to two angles of another triangle, then the third angles are congruent.
Each angle of an equiangular triangle has a measure 60
In a triangle, there can be at most one right angle
a polygon such that no line containing a side of the polygon contains a point in the interior of the polygon.
A segment joining two nonconsecutive vertices
The sum of the measure of the angles of a convex polygon with n sides is (n-2)180
The sum of the measures of the extrior angles of any convex polygon, one angle must be a vertex, is 360.