However, we can use angles in such a way that we never have any estimate that correlates with the size of the rectangle whose aspect ratio we are measuring.<p>Suppose some rectangle is visible at a distance. We can use parallax angles from our vantage point to estimate its aspect ratio.<p>We have no idea how long or wide that rectangle is because we don&#x27;t know how far away it is.<p>(Indeed, we don&#x27;t even know whether it is a rectangle, or whether it is some quadrilateral that appears as a rectangle under perspective.)