McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Rhombi and Squares
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Exercise 10 Page 517

The diagonals of a rhombus bisect each other.

PD=5

Practice makes perfect

Let's analyze the given rhombus.

To find the length PD we must first find the value of x. First, by the Segment Addition Postulate, we can express the diagonal DB as the sum of PB and PD. DB= PB+PD

For all rhombi, the diagonals bisect each other. Therefore, the lengths of PB and PD are equal. We can use this fact to rewrite the Segment Addition Postulate equation in terms of the given expressions, DB= 2x-4 and PB=2x-9.

Equation DB= PB+PD
Substitution DB= PB+ PB
Simplification DB=2PB
Substitution 2x-4=2(2x-9)
Now we can solve this equation for x.
2x-4=2(2x-9)
â–Ľ
Solve for x
2x-4=4x-18
2x=4x-14
-2x=-14
x=7
Finally, we can find PD using the value of x we found. As previously mentioned, we know that the lengths of PB and PD are equal. Therefore, we can use the given expression for the length of PB to find PD. lPD=PB PB=2x-9 ⇒ PD=2x-9 Let's substitute x=7 into this equation to find PD.
PD=2x-9
PD=2( 7)-9
â–Ľ
Evaluate right-hand side
PD=14-9
PD=5
We found that the length of PD is 5.