Name _____________________________________ Class _____________ Date ____________
Practice 3-2
Proving Lines Parallel
1. Developing Proof Complete the paragraph proof for the figure shown.
Given:
and
and
are supplementary.
are supplementary.
Prove:
Proof Because
and
are supplementary,
and
are a. __?__ angles. By the Same-Side Interior Angles
Theorem, b. __?__ c. __?__. Because
and
are
supplementary,
and
are d. __?__ angles. By the
e. __?__ Theorem,
. Because
are parallel to f. __?__,
and
both
by Theorem g. __?__.
Which lines or segments are parallel? Justify your answer with a theorem or postulate.
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7.
Algebra Find the value of x for which
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