Question 16****+Do \(\mathbf r=(1,0,0)+s(1,1,0)\) and \(\mathbf r=(0,1,1)+t(1,1,0)\) represent the same line?
Question 18*****Find the line through \((2,0,-1)\) parallel to \((1,-1,2)\), and show that this line is parallel to the plane with normal \((1,1,0)\).
Question 19*****Decide whether \((4,6)\) lies on the segment from \((1,0)\) to \((5,8)\), then find the ratio in which it divides the segment.
Question 20*****Find the shortest distance between the parallel lines \(\ell_1:(0,0)+s(1,0)\) and \(\ell_2:(0,3)+t(1,0)\), and identify one pair of closest points.