Question

what is Tan of -90? :/

Answer 1

\[\tan x=\frac{ \sin x }{ \cos x }\]

Now at -90 or +90 cosx=0
And we cannot divide by 0, this means that we do not know exactly what happens at 0.

Answer 2

tan(-90)=-tan90=-infinite as tan90=sin90/cos90 and cos90=0 also 1/0=infinte so we get -infinite