What is the largest equilateral triangle that can be inscribed in a circle?

Let r be the radius.the area of the triangle is3×1/2×r×r×sin120= 3(sqrt3)(r^2)/4

The answer would he -4,-2 because the points are just on the opposite side. since the x axis is +4 it's going to he -4 and since the y axis is -2 it stays there because whaen rotated it stays in the third quadrant