It is possible to draw a maximum of one tangent to a circle from a point, which lies in the exterior of the circle. 

One and only one tangent can be drawn from a point on the circle.  

Length of tangent drawn from an external point $P$ on a circle $C(O, r)$ is always greater than $OP$.

Length of tangent from an external point on a circle is always less than the radius of the circle.

$$If a chord $PQ$ subtends an angle of $70°$ at the centre of a circle, then angle between the tangents at $P$ and $Q$ is also $70°$.