Objective

To verify that the tangent at any point to a circle is perpendicular to the radius through that point of contact.

Theory

1) What is tangent?

       A line that touches the circle at a single point is known as tangent to a circle.

                                                   Fig. (A) Tangent to the circle

2) What is the radius of a circle?

     The distance from the centre of a circle to the outside edge. See Fig (B).

                                                       Fig. (B) Radius of the circle

3) What is perpendicular angle?

   Perpendicular lines are lines that intersect at a right (90˚) angle. See Fig (C).

                                                          Fig (C) Perpendicular angle

4) Maths rule:

  Shortest distance between a point and line is perpendicular distance.