Answer: approximately 582 feet.
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Work Shown:
Let
x = length of AD in feet
y = length of DC in feet
x and y are positive real numbers.
For now, focus on triangle BCD. Ignore point A and its associated angle.
tan(angle) = opposite/adjacent
tan(D) = BC/DC
tan(16) = 125/y
y*tan(16) = 125
y = 125/tan(16)
y = 435.926805480113
y = 435.926805
The value of y is approximate
Now focus on triangle ABC. Ignore point D and its associated angle.
tan(angle) = opposite/adjacent
tan(A) = BC/AC
tan(A) = BC/(AD+DC)
tan(7) = 125/(x + y)
(x+y)*tan(7) = 125
x*tan(7) + y*tan(7) = 125
x*tan(7) = 125 - y*tan(7)
x = ( 125-y*tan(7) )/( tan(7) )
x = ( 125-435.926805*tan(7) )/( tan(7) )
x = 582.116498496824
x = 582
The distance from A to D is approximately 582 feet.
