The two parallel bars mean absolute value meaning the positive value of that number. The positive value of -8 is 8. Note that positive number in an absolute value bars reamin the same.
The horizontal distance is given by the formula: tan θ=opposite/adjacent where: θ=21 opposite=2000 ft adjacent=a thus calculating for a we get: tan 21=2000/a thus a=2000/tan 21 a=5210.18 ft
