Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
5. Using Parallel and Perpendicular Lines
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Exercise 26 Page 532

Statements
Reasons
1.
a and b are vertical lines.
1.
Given.
2.
a and b are perpendicular to a horizontal line c.
2.
Slopes of Perpendicular Lines Theorem.
3.
a and b are parallel lines.
3.
Lines Perpendicular to a Transversal Theorem.
Practice makes perfect

Let a and b be two vertical lines, being cut by a horizontal transversal c. By the Slopes of Perpendicular Lines Theorem, a and b are both perpendicular to c.

Slopes of Perpendicular Lines Theorem a⊥ c and b⊥ c

By the Lines Perpendicular to a Transversal Theorem, we have that a and b are parallel lines.

Lines Perpendicular to a Transversal Theorem a∥ b We can summarize our proof in a two-column proof table.

Statements
Reasons
1.
a and b are vertical lines.
1.
Given.
2.
a and b are perpendicular to a horizontal line c.
2.
Slopes of Perpendicular Lines Theorem.
3.
a and b are parallel lines.
3.
Lines Perpendicular to a Transversal Theorem.