Assertion: line's slope | /r/HasProperty | denoted by the letter m
Facets:
value: often
type: TEMPORAL
Source sentences:
text: Slope is often denoted by the letter m; there is no clear answer to the question why the letter m is used for slope, but its earliest use in English appears in O'Brien (1844) who wrote the equation of a straight line as "y = mx + b" and it can also be found in Todhunter (1888) who wrote it as "y = mx + c".