With that information you can determine how far the park is from the football field.
Call h the height of the triangle, x the distance from the park to the football field and y the distance from the park to the home of Kristen.
Using Pithagora's theorem, ou can state this system of equations:
1) From the complet triangle: x^2 + y^2 = (8 + 2)^2 = 10^2 = 100
2) From the triangle whose hypotenuse is the distance from the park to the football field:
x^2 = 8^2 + h^2
3) From the triangle whose hypotenuse is the distance from the park to the home of Kristen:
y^2 = 2^2 + h^2
To solve the system start by subtracting equation 3) from equation 1) =>
x^2 + y^2 = 100
y^2 = 4 + h^2
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x^2 = 100 - 4 - h^2
x^2 = 96 - h^2
Now sum this result to equation 2
x^2 = 96 - h^2
x^2 = 64 + h^2
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2x^2 = 96 + 64
2x^2 = 160
=> x^2 = 80
=> x = 8.94
Answer: 8.94 miles
Neither because they bot weigh a pound
Plan 1 because she spends 435.88 more if she goes with plan 2