## Geometry: Common Core (15th Edition)

Published by Prentice Hall

# Chapter 3 - Parallel and Perpendicular Lines - 3-3 Proving Lines Parallel - Practice and Problem-Solving Exercises - Page 162: 33

#### Answer

$x=2.5$ $m\angle1=30$ $m\angle2=30$

#### Work Step by Step

Angles 1 and 2 are in corresponding positions relative to the 4 angles created when the transversal intersects with line r and the 4 angles created when the transversal intersects with line s. The Converse of the Corresponding Angles Theorem tells us that the lines are parallel when $\angle1\cong\angle2$, or, by the definition of congruency, when $m\angle1=m\angle2$. Write and solve an equation to find the value of x when the lines are parallel. $m\angle1=m\angle2$ $40-4x=50-8x\longrightarrow$ substitution $40+4x=50\longrightarrow$ addition property of equality $4x=10\longrightarrow$ subtraction property of equality $x=2.5\longrightarrow$ division property of equality Substitute to find the measue of each angle. $m\angle1=40-4x=40-4(2.5)=40-10=30$ $m\angle2=50-8x=50-8(2.5)=50-20=30$

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