# 1.1 Angles and Lines II

1.1 Angles and Lines II

Identifying Parallel, Transversals, Corresponding Angles, Alternate Angles and Interior Angles
(A) Parallel lines
Parallel lines are lines with the same direction. They remain the same distance apart and never meet.

(B) Transversal lines
A transversal is a straight line that intersects two or more straight lines.

(C)
Alternate angles

(D) Corresponding angles

(E) Interior angles

PT3 Smart TIP

Alternate angles are easily identified by tracing out the pattern “Z” as shown.

Corresponding angles are easily identified by the pattern “F” as shown.

Interior angles are easily identified by the pattern “C” as shown.

Example 1:
In Diagram below,PQ is parallel to RS. Determine the value of y.

Solution:

Construct a line parallel to PQ and passing through W.
= 40o and b = 50o← (Alternate angles)
= a + b
= 40o+ 50o
= 90o

Example 2:
In Diagram below, PSQ and STU are straight lines. Find the value of x.
Solution:
$\begin{array}{l}\angle WSQ={180}^{o}-{150}^{o}\\ \text{}={30}^{o}←\overline{)\text{Supplementary angle}}\\ \angle XTU=\angle WSQ+\angle x←\overline{)\text{Corresponding angle}}\\ \text{}{75}^{o}={30}^{o}+\angle x\\ \text{}\angle x={75}^{o}-{30}^{o}\\ \text{}\angle x={45}^{o}\\ \text{}x=45\end{array}$