Answer:
(a×b)×c = 0 means that vector c parallel to vector (a×b). But because (a × b) ⊥ a and (a -b) ⊥ b so
c ⊥ a and c ⊥ b.
Hope this helps, have a nice day! :D
<h2>
Hello!</h2>
The answers are:

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Why?</h2>
Since we are given the margin of error and it's equal to ±0.1 feet, and we know the surveyed distance, we can calculate the maximum and minimum distance. We must remember that margin of errors usually involves and maximum and minimum margin of a measure, and it means that the real measure will not be greater or less than the values located at the margins.
We know that the surveyed distance is 1200 feet with a margin of error of ±0.1 feet, so, we can calculate the maximum and minimum distances that the reader could assume in the following way:


Have a nice day!
Use photmath app it will help you out:)
Answer:
<h2>hope it helps you see the attachment for further information </h2>