Q. #3: Forces of magnitude P, 2P, 3P, 4P act respectively along the sides AB, BC, CD, DA of a square ABCD, of a side a and forces each of magnitude (82)P act along the diagonals BE, AC. Find the magnitude of the resultant force and the distance of its line of action from A. Q. #4: Forces P1, P2, P3, P4, P5, P6 act along the sides of a regular hexagon taken in order. Show that they will be in equilibrium if P = 0 and P-P = P3-P6 = P5 - P2. Q. #5: Find the most general function differentiable function f(r) so that f(r) is solenoidal.