In the latter work al-Tusi discussed objections raised by earlier mathematicians to comparing lengths of straight lines and of curved lines. Al-Tusi argues that comparisons are legitimate, despite the objections that, being different entities, they are incomparable.
Sa huli ng trabaho al-Tusi tinalakay objections itataas sa pamamagitan ng mas maaga mathematicians sa paghahambing ng haba ng tuwid na linya at ng tuwid na linya. Al-Tusi argues na paghahambing ay lehitimong, sa kabila ng objections na, sa iba't-ibang entidad, sila ay walang kawangis.