http://www.ck12.org Chapter 3. Parallel and Perpendicular Lines
Solution:The given angles are same side interior angles. The lines are parallel, therefore the angles add up to 180◦.
Write an equation.
( 2 x+ 43 )◦+( 2 x− 3 )◦= 180 ◦
( 4 x+ 40 )◦= 180 ◦
4 x= 140 ◦
x= 35 ◦While you might notice other angle relationships, there are no more theorems to worry about. However, we will
continue to explore these other angle relationships. For example, same side exterior angles are also supplementary.
You will prove this in the review questions.
Example 9:l||mands||t. Prove^61 ∼=^6 16.
Solution:
TABLE3.2:
Statement Reason
1.l||mands||t Given2.^61 ∼=^63 Corresponding Angles Postulate
3.^63 ∼=^616 Alternate Exterior Angles Theorem
4.^61 ∼=^616 Transitive PoC
Know What? RevisitedUsing what we have learned in this lesson, the other angles that are 35◦are^6 T LQ,^6 ET L,
and the vertical angle with^6 T LQ. The other angles that are 160◦are^6 F SR,^6 T SQ, and the vertical angle with