Angles Formed byParallel Lines & cut by a

Transversals

When two parallel lines are given in a figure, there are two main areas: the interior and the exterior. 

When two parallel lines are cut by a third line, the third line is called the transversal. In the example below, eight angles are formed when parallel lines m and n are cut by a transversal line, t.

• transversal is a line that intersects two or more lines (in the same plane).  When lines intersect, angles are formed in several locations.  Certain angles are given "names" that describe "where" the angles are located in relation to the lines.  These names describe angles whether the lines involved are parallel or not parallel.

Alternate interior angles

•two angles in the interior of the parallel lines, and on opposite (alternate) sides of the transversal. Alternate interior angles are non-adjacent and

congruent. 

Alternate exterior angles

• two angles in the exterior of the parallel lines, and on opposite (alternate) sides of the transversal. Alternate exterior angles are non-adjacent and congruent. 

Corresponding angles

• two angles, one in the interior and one in the exterior, that are on the same side of the transversal. Corresponding angles are non-adjacent and congruent.

Interior Angles on the Same Side of the Transversal

• (measures are supplementary)Their "name" is simply a description of where the angles are

located.

Vertical Angles

• (measures are equal)Vertical angles are ALWAYS equal, whether youhave parallel lines or not.

• (measures are equal)Vertical angles are ALWAYS equal, whether youhave parallel lines or not.

Summary• Parallel lines are lines that never meet.• A transversal is a line that intersects 2 or more

(parallel) lines.• Parallel lines cut by a transversal form 8 angles.• Pairs of angles will be either congruent or

supplementary.• Vertical angles are ALWAYS equal, whether you

have parallel lines or not.

Angles forming a Linear Pair 

• (measures are supplementary)

• 

Theorem:•If two angles form a linear pair, they are supplementary.

SOURCE !…

• http://www.math10.com/en/geometry/angles/angles.html

• l•http://www.regentsprep.org/Regents/math/geometry/GP8/Lparallel.htm

III - MASUNURIN

• Teacher :

• Mr. Cristopher M. Magto

MEMBERS:

• LOVELY JANE LARIEGO

• HANNA MAE RUBILLAR

LEA LLAGAS

Video of ANGLE FORMED BY PARALLEL LINES CUT BY A

TRANSVERSAL

• http://www.youtube.com/watch?feature=player_detailpage&v=iHfOtyq2OtU#t=15