Originally Posted by

**zhandele** The attached pdf may help you. If that equation "has equal roots," that means the disciminant b^s -4ac must be equal to zero.

The two tangents are not "equal", but they are perpendicular. There are two unequal values of k for which that equation has equal roots. Perhaps you were looking for equal values of k and that's what confused you? Just guessing.

The point of the exercise seems to be that through any point external to the circle, two tangents can be constructed.