Answer: y = 5
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Explanation:
For any rectangle, the diagonals are always the same length. We can use congruent triangles to prove this.
This means AC = BD.
Also, the diagonals of a rectangle cut each other in half (bisect). This indicates the following two equations
We'll use that second equation along with BP = -2x+23 and DP = 3y-6 to form the equation -2x+23 = 3y-6. This will be used later.
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By the segment addition postulate, we know that
BP+DP = BD
(-2x+23)+(3y-6) = BD
BD = -2x+3y+17
Since the diagonals are equal, we also know that AC = -2x+3y+17
We are given that AC = 2x+4
Equating the two right hand sides leads to the equation 2x+4 = -2x+3y+17
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The conclusion of each the last two sections was the following two equations
- -2x+23 = 3y-6
- 2x+4 = -2x+3y+17
We have two equations and two unknowns. We have enough info to be able to find x and y.
Let's isolate 3y in the first equation
-2x+23 = 3y-6
3y-6 = -2x+23
3y = -2x+23+6
3y = -2x+29
Then we can plug this into the second equation
2x+4 = -2x+3y+17
2x+4 = -2x+(3y)+17
2x+4 = -2x+(-2x+29)+17 .... replace 3y with -2x+29
Now solve for x
2x+4 = -2x+(-2x+29)+17
2x+4 = -2x-2x+29+17
2x+4 = -4x+46
2x+4x = 46-4
6x = 42
x = 42/6
x = 7
We then use this to find y
3y = -2x+29
3y = -2(7)+29
3y = -14+29
3y = 15
y = 15/3
y = 5
