McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
2. Parallelograms
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Exercise 20 Page 490

Recall the theorem that states if a quadrilateral is a parallelogram, then its diagonals bisect each other.

y=5, z=2

Practice makes perfect

We want to find the values of y and z for which JKLM is a parallelogram, using the given algebraic expressions for the segment lengths. For convenience we will label the point of intersection of the diagonals T.

Recall the following theorem.

Parallelogram Diagonals Theorem

If a quadrilateral is a parallelogram, then the diagonals bisect each other.

Therefore, the following segments are congruent. JT ≅ TL and MT ≅ TK By the definition of congruent segments, we can conclude that their lengths are equal. JT = TL and MT = TK Let's create two equations by substituting the lengths of the segments into these equations. 3y - 5 = y + 5 and z + 9 = 2z + 7 Let's start by solving the first equation for y.
3y - 5 = y + 5
3y = y + 10
2y = 10
y = 5
Now, we can obtain z by solving the second equation.
z + 9 = 2z + 7
9 = z + 7
2 = z
z = 2