11. x2+12-3x+2=0, 2x2+212-5x-√3y+3=0, 2x2+212-7x+√31 +6 = 0. 7. The focus is a point 30 ft. below the point from which the ball was dropped; the directrix is a line parallel to the direction of the train 30 ft. above the roof. 8. 10. (i.) 1200 lbs. ; (ii.) 34800 lbs. 9. (i.) 1:3; (ii.) 1:2e+1. |