Respuesta :
in a function we can say f(x) = y
y = f(x) = tan(90°)
y = f(x) = ∞ (undefined)
y = f(x) = tan(90°)
y = f(x) = ∞ (undefined)
f(x) = tan90° ⇒ y = tan90°
tan90° non exist, therefore the y-value not exist.
tan90° non exist, therefore the y-value not exist.