Rafael Algorithm Developer interview questions

One of the problems was the knapsack problem.

1) I was asked about my current job 2) Given a binary image of a single line that cross the image. How to tell what the angle of the camera that need to be changed to take the picture so that the line would be parallel to one of the image borders. 3) The line in reality is at slightly different points than seen in the image since a quantization process for signals occurs while taking a picture. How can we accurate the angle from question 2 so that it is more precisely in reality.