Horizontal lines have a slope of zero and are parallel to the x-axis. In terms of functions, if the slope field consists only of horizontal lines, it means that every tangent line has zero slope for all values of x.
Related terms
Slope: The measure of steepness or incline between two points on a graph.
Vertical Lines: Lines with undefined slopes that run parallel to the y-axis.
Steepest Descent/Ascent Line: The tangent line with maximum positive/negative slope at any given point in the slope field.