JEE Main & Advanced Mathematics Circle and System of Circles Director Circle

Director Circle

Category : JEE Main & Advanced

The locus of the point of intersection of two perpendicular tangents to a circle is called the Director circle.

 

 

Let the circle be \[{{x}^{2}}+{{y}^{2}}={{a}^{2}}\], then equation of director circle is \[{{x}^{2}}+{{y}^{2}}=2{{a}^{2}}\].

 

 

Obviously director circle is a concentric circle whose radius is \[\sqrt{2}\] times the radius of the given circle.

Director circle of circle \[{{x}^{2}}+{{y}^{2}}+2gx+2fy+c=0\] is \[{{x}^{2}}+{{y}^{2}}+2gx+2fy+2c-{{g}^{2}}-{{f}^{2}}=0\].

 


You need to login to perform this action.
You will be redirected in 3 sec spinner