Here we can clearly see two free points A and B. B is a point from which tangents to the circle are drawn and A is the center of the circle. We can change the size and the position of the given circle by moving free point A and position of the tangents by moving free point B. BD and BC are the lengths of the tangents from the point B to the given circle.

Questions to think about
1. Move the points A and B and compare the lengths of BD and BC what do we observe?
2. Is it possible to get BD≠BC?