Explanation:
Parallel (geometry)
Two lines in a
plane that do not intersect or meet are called parallel lines.
Symbol
The parallel symbol is .
For example, indicates
that line AB is parallel to line CD.
Lines a and b are parallel.
http://en.wikipedia.org/wiki/Parallel_(geometry)
Transversal line
In geometry, a transversal line is a line that passes through two or more other coplanar lines at different points.
In Euclidean geometry if lines a and b are parallel, and line t intersects lines a and b, then corresponding angles formed by line t and the parallel lines are congruent.
Theorem 9 If a transversal
intersects two parallel lines then the alternate interior angles are congruent.
Theorem 10 If a transversal
intersects two parallel lines then the corresponding angles are congruent. (Our solved example in
mathguru.com uses this concept)
Theorem 11 If a transversal
intersects two parallel lines then the alternate exterior angles are congruent.
Theorem 12 If a transversal
intersects two parallel lines, then the interior angles on the same side of the
transversal are supplementary. (Our solved example in mathguru.com uses this concept)
http://en.wikipedia.org/wiki/Transversal_line
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