reading comprehensive

[shahar]

In:

Vertical Tangents and Cusps

Calculus

www.sosmath.com

I don't understand the sentence:
In the definition of the slope, vertical lines were excluded

What the meaning of excluded?
what the writer means?

 

[Harry_the_cat]

The definition does not apply to vertical lines.

 

[shahar]

The definition does not apply to vertical lines.

OK. Now it is understood.