Why sine bar cannot measure an angle greater than 45 degrees?

A sine bar cannot measure angles greater than 45 degrees effectively because, at angles beyond this, the sine function approaches its maximum value of 1, leading to very small differences in height for small changes in angle. This results in reduced measurement accuracy and sensitivity, as the required height adjustments become increasingly difficult to measure precisely. Additionally, the geometry of the sine bar makes it less stable and harder to align accurately at higher angles. Thus, for angles greater than 45 degrees, other measuring tools are typically preferred.