Тимур Покровский

bool func (double x1, double y1, double x2, double y2, double x3, double y3, double x, double y) {
    return (((x - x1)*(y2 - y1) - (y - y1)*(x2 - x1))*((x3 - x1)*(y2 - y1) - (y3 - y1)*(x2 - x1)) >= 0) &&
           (((x - x2)*(y3 - y2) - (y - y2)*(x3 - x2))*((x1 - x2)*(y3 - y2) - (y1 - y2)*(x3 - x2)) >= 0) &&
           (((x - x3)*(y1 - y3) - (y - y3)*(x1 - x3))*((x2 - x3)*(y1 - y3) - (y2 - y3)*(x1 - x3)) >= 0)
}

Item item = items.Find(i => i.ItemName == "Ball");
if (item != null) {
	item.ItemID = 8;
	item.ItemCost = 1000;
}