It can be analyzed that when point T moves to the right, S 1 increases and S2 decreases. Because the bottom of S2 is longer than the top of S 1, S2 decreases quickly, while S 1 increases slowly, and the total area decreases. When the span of both sides is the same, the increase and decrease speed is the same, and the total area decreases to the minimum, and then increases, so the smallest point should be the point where x=0.5.