6.2

Theorem 6-1

Opposite sides of a parallelogram are congruent
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Theorem 6-2

Opposite angles of a parallelogram are congruent
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Theorem 6-3

The diagonals of a parallelogram bisect each other
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Theorem 6-4

If three (or more) parallel lines cut of congruent segments on one transversal, then they cut off congruent segments on every transversal
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Example Theroem 1

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180-53= x


127= x


The angle opposite of the angle with 53 degrees, is 53 degrees. The missing angle, x, is 127, and so is the angle opposite of it.

Example Theorem 2

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3x + 2 = 14


3x = 12


X = 4



3(4) + 2 = 14

Example Theorem 3

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Number 18


PT= x + 2 and TR= y

QT= 2x and TS= y + 3


x + 2 = y


2x = X + 2 + 3


X = 5


(5) + 2 = y


Y= 7