Arctan(x) = Pi means x = tan(pi)
[tex] tan(\pi) = \frac{0up}{1left} = 0 [/tex]
Arctan(x) = 0 means x = tan(0)
[tex] tan(0) = \frac{0up}{1right} = 0 [/tex]
Get it?
2. The answer is in limits.
[tex] arctan(1/0) = undefined [/tex]
However the limit is defined:
[tex] \lim x\rightarrow 0 \mbox{ of } arctan(1/x) = \frac{\pi}{2} [/tex]
Try graphing the function arctan(x) and use the trace tool to see the values at those points.
