m stands for "modulus of slope"; modulus means "number used to measure." We now call the slope just simply "slope" but still use "m" to indicate it in the formula.
M refers to the modulus of the slope.
m = slope
The slope of a line perpendicular to one with a slope of m is -1/m.
If the slope of a line is m then the slope of an altitude to that line is -1/m.
Slope of a line = m slope of perpendicular line = -1/m
If we call the slope m we can say that the slope of the perpendicular line is -1/m In this case as the slope, m, is 13 the slope of the perpendicular is -1/13 or -0.07692307692
It is the slope.
slope = m = (∆y) / (∆x) = rise / run
The formula for the slope of a line in mathematics is m = y2 - y1/x2 - x1. The slop of the line describes the steepness so a higher value slope means a steeper slope.
It is not documented why the letter m was chosen for slope. However, mathematician John Conway suggested that m could mean 'modulus of slope'.