Error in Computing Undefined

[rsr20]

Hey all, sorry if this has been answered before. I've been searching for a solution on here and Google for over an hour to no avail. My calculator returns a number for what should be an undefined problem. This has happened for others but the specific problem I'm working on currently is:

(When set to Radians) ==> tan(pi/2) = -195,948,537,906
_____--- and --- ________ tan(-pi/2) = 195,948,537,906

(When set to Degrees) ==> tan(90) = Error: /inf result

I would expect the same answer that appears in degrees to appear in the radians setting. I've also noticed that the calculator sometimes returns a very small number when the answer should be zero. This doesn't happen frequently and I haven't noticed a pattern yet, but it's enough of an issue to cause problems when computing engineering problems that require accuracy.

Is this a common problem and is there a fix for it?

Thanks,

-Roscoe