The specific epithet "squarrosus" refers to the leaves, which are squarrose, having a right-angled bend which causes the tips to extend away from the stem.
Therefore, in a right-angled triangle, the two non-right angles total 90 (/2 radians), so each of these angles must be in the range of (0,90) as expressed in interval notation.
In medieval architecture, the knotted rope was indispensable for architects, because it allowed the construction of equilateral and right-angled triangles, as well as circles.
