8) The line of intersection between cylinder an cone, unless they envelop a common sphere is made up of?

9) When a solid completely penetrate another solids there will be two lines of intersection. These lines are called as

10) If a plane cuts a cone at an angle and it cuts all the generators, then the conic curve is called as

11) Two surface planes intersect in a ______ line?

12) A cylinder is placed on H.P. on its base and section plane is parallel to H.P., then the section of solid gives