lim f(X) = lim arctg (1/(1-x^2) when x-->1
Substitute with x=1
lim f(x) = arctg lim (1/0)
But we know that arctg = arcsin/arccos
==> arctg (1/0) = arc(sin(pi/2)/cos(pi/2)
= arctg(pi/2)
= pi/2
Math
lim f(X) = lim arctg (1/(1-x^2) when x-->1
Substitute with x=1
lim f(x) = arctg lim (1/0)
But we know that arctg = arcsin/arccos
==> arctg (1/0) = arc(sin(pi/2)/cos(pi/2)
= arctg(pi/2)
= pi/2