Question

Why an angle is made up of rays and not of lines or line segments?

Answer 1

$\huge\underline\mathfrak\red{AnSweR}$

$\textbf{Explanation:}$

If two line meet but are not perpendicular, then two angles are formed: one acute and one obtuse. So "line" came to mean "infinitely long line". And te more easily distinguish the angles formed by intersecting lines, angles were formed from rays. (Infinite in one direction, but sharing a common endpoint.)