Tangents drawn from an external point
1)A tangent to a circle intersects it in how many points ? 
  

2)How many parallel tangents can a circle have at the most ? 
  

3)A line intersecting a circle in two points in called 
  

4)A tangent AB at a point A of a circle of radius 5 cm meets a line through the centre O at a point B so that OB = 13 cm. Length AB is 
  

5)From a point A, the length of the tangent to a circle is 4 cm and the distance of A from the centre is 5 cm. The radius of the circle is