4a. [2 marks] Consider points A(1, -2, -1) , B(7, -4, 3) and C(1, -2,3) . The line Ll passes through C and is parallel to AB . Find AB . 4b. [2 marks] Hence, write down a vector equation for 21 . 4c. [3 marks] T = 2 + s -3 A second line, 2 , is given by 15 P Given that 1 is perpendicular to 2 , show that P = -6. 4d. [7 marks] The line 1 intersects the line -2 at point Q. Find the F-coordinate of