There are problems with both pictures. Let's start with the first one. Let's compare the length of one to one millimeter. The area of the big triangle is 12, the small triangle is 5, and the total area of red and yellow is 15. It adds up to 32. How can your overall area be 32.5 15? It just fits in the area of 15.5, and there is a critical point here, which is 15.5. I just need to lower the height of the rectangle by 0. 1 mm, which is just the area of 15, that is, I can just fit two red and yellow rectangles. Then the second picture. The area of the same four building blocks is 32, but the total area is 32.5. How does the same area of 16 fit into a rectangle with an area of 15.5? As long as I raise the height by 0.0625mm, the area of the rectangle is 16, and the area of the red and yellow pieces is 15, so it is empty. The naked eye can't see the difference between 0. 1 mm and 0.0625 mm, so the method to calculate the visual error point is to calculate the area of four building blocks, which is 32. Combine the whole triangles of the two pictures into a rectangle with an area of 65, and the problem will be clear. The total building block area of the two pictures is 64. If you put it in a rectangle with an area of 65, you will definitely lose one, okay?