Hello!
Part A:
The equation for a circle is (x - a)^2 + (y - b)^2 = r^2
We can say that the center of the earth is point (0, 0)
This gives us the equation
x^2 + y^2 = 3960^2
Square the number
x^2 + y^2 = 15681600
The answer is C
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Part B
The answer is C) 69 miles
Hope this helps!
