AP EAMCET Engineering 26 Apr 2017 Shift 1 Paper

Consider the figure shown below.Therefore,
AO=

2

3

AD
=

2

3

×9
=6
Now, O is the circumcentre of ΔABC.
In an equilateral triangle circumcentre, incentrem centroid coincide.
Therefore,
AO is the radius of the circle.
Thus, the equation of circle is,
x2+y2=62
x2+y2=36