An infinitely thin, -long squeegee begins to slide down from the upper-left corner of a square window. Its other end simultaneously slides toward the lower-right corner of the window, with the upper end kept in contact with the left side of the window.
If , what is the area of the window in cleaned by the squeegee?
Note: you may end up with an integral expression that's difficult to evaluate analytically. Feel free to finish the job using the code environment below: