求两圆相交面积 两圆半径分别问ar,br,两圆圆心距为d-Seeking two circles intersect area radius Q ar, br, two round Heart distance is d if ar+ br < d return 0　two circles from else if (fabs (ar-br),>　d return area (min (ar , br)) of two circles covering else the two circles intersect can know the focus and center of the circle of the two circles intersect to form a quadrilateral, constitute then a fan-shaped area is S = a fan-shaped area of ​　​　+ b fan-shaped area- the quadrilateral area of ​　​　intersection with each round heart