Correct answer: {−1, 3}
The area of triangle ABC can be calculated using the formula for the area of a triangle, which is 1/2 * base * height. Given that AC is the hypotenuse, the height can be determined by the vertical distance from point B to line AC, and the base is the horizontal distance between points A and C. Solving the area equation leads to the values of k being -1 and 3.