What is the answer for question 6) http://postimg.org/image/ypiv1yj7r/
Let L be a line and C be a circle. Line L is intersecting circle C at two points say P and Q.Since L is intersecting C at two points ,so it will be known as secant. If either P approaches to Q or Q approaches to P then the point of intersectin of L and C will be unique point. So L will be known as tangent to curve C.It means the limiting condition of the secant line is tangent line.