the main equation of the circle is (x-x1)²+(y-y1)²=R² where C(x1, y1) is the center so if the center is the origin, it is O(0,0), and the equation becomes <span> (x)²+(y)²=R² </span>and the circle passes through the point (-5,2) so we can write (-5)²+12²=R², it implies R= sqrt(25+144)=sqrt(169)=13
and for <span>B(11, 2sqrt(12) ) </span>11²+ (2sqrt(12))²= 121 + 48= 169= 13 it is checked.
