This document discusses angles formed when parallel lines are cut by a transversal line. It defines key terms like parallel lines, transversal, and describes angle pairs that are formed - alternate interior angles, alternate exterior angles, corresponding angles, interior angles on the same side of the transversal, and vertical angles. It notes that alternate interior angles, alternate exterior angles, and corresponding angles are congruent, while interior angles on the same side of the transversal are supplementary. Vertical angles are always equal.

1. Angles Formed by
Parallel Lines & cut by a
Transversals

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

3. 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.

4. 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.

5. 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.

6. 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 nonadjacent and congruent.

7. Interior Angles on the Same
Side of the Transversal
• (measures are supplementary)
Their "name" is simply a description of where the angles are
located.

8. Vertical Angles
•• (measures are equal)
(measures are equal)
Vertical angles are ALWAYS equal, whether
Vertical angles are ALWAYS equal, whether
you
you
have parallel lines or not. .
have parallel lines or not

9. 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.

10. •
Angles forming
a Linear Pair
• (measures
Theorem:
are supplementary)
•If two angles form a linear pair, they
are supplementary.

11. SOURCE !…
• http://www.math10.com/en/geometry/angl
es/angles.html
•
•http://www.regentsprep.org/Regents/m
l ath/geometry/GP8/Lparallel.htm

12. III - MASUNURIN
• Teacher :
• Mr. Cristopher M. Magto

13. MEMBERS:
• LOVELY JANE LARIEGO
• HANNA MAE RUBILLAR
LEA LLAGAS

14. Video of ANGLE FORMED BY
PARALLEL LINES CUT BY A
TRANSVERSAL
• http://www.youtube.com/watch?
feature=player_detailpage&v=iHfOtyq2Ot
U#t=15