Parallel lines remain at a constant distance apart and never intersect. When a transversal line crosses two parallel lines, four types of angles are formed: corresponding angles are in the same relative position on both sides of the transversal and are equal, alternate angles are on opposite sides of the transversal and are equal, interior angles are inside the parallel lines and their sums are 180 degrees, and exterior angles are outside the parallel lines and their sums are also 180 degrees. Examples are given to illustrate each type of angle.

1. Lines and Angles II

2. Parallel lines are straight lines that do not meet and remain at the same distance apart.
Example:
A B
C D
Line AB and CD are parallel lines.

3. A transversal is a straight line that intersects two or more parallel lines.
Example:
x
A B
C D
y
Line xy is a transversal.

4. Corresponding angles :
Two angles that are located in the same relative location. If a transversal intersects two parallel
lines, corresponding angles appear on the same side of the transversal.
Example:
Thus, the
corresponding angles
are
d and f ;
b and h;
a and g;
c and e.
And;
d=f;
b=h;
a = g;
c=e

5. Alternate angles:
Two angles, not adjoining one another, that are formed on opposite sides of a line that
intersects two other lines. If the original two lines are parallel, the alternate angles are equal.
Example:
Thus, the alternate angles
are:
a and e;
d and h;
b and f;
c and g
And;
a=e
d=h
b=f
c=g

6. Interior angles:
When two lines are cut by a transversal, the angles that are formed on the inside of the two
lines are known as interior angles.
Example :
Thus, the interior angles
are:
d and e;
f and c;
a and h;
b and g
And;
d + e = 180⁰
f + c = 180⁰
a + h = 180⁰
b + g = 180⁰

7. Interior angles:
When two lines are cut by a transversal, the angles that are formed on the inside of the two
lines are known as interior angles.
Example :
Thus, the interior angles
are:
d and e;
f and c;
a and h;
b and g
And;
d + e = 180⁰
f + c = 180⁰
a + h = 180⁰
b + g = 180⁰