Arctan to radians.. need help asap..

Hello experts,

ok, so heres my problem..
I have these 2 problems: phi = arctan (2/3) = .588 rad
and
phi = arctac(-8/1) = -1.446 rad

My question is that how do you get .588 and -1.446? Can someone please explain me this carefully?

by the way we are allowed to use calculator on tomorrows exam but i dont know how to get those number using the calculator.. I have a Ti-Nspire.. Any help would be great.
thanks a lot

arc tan ... is the inverse function of tan

so on an older calculator you punch the number in first..

so you type...

2
then /
then 3

then inverse button ' INV" or SECOND FUNCTION putton for the function above the key

then TAN KEY

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make sure it is in RADIANS MODE not decimal

you can press the DRG button to change modes I think


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the second one same thing


8
then -/+
then second function or INV key
then TAN

that is all there is to it..

you need to use the calculator to find these angles

depending on your calculator, it will be 2nd tan or inverse tan (but should have the symbol tan^-1

tan^-1 (2/3) = .588 (from calculator)
tan^-1 (-8) = -1.446 (from calculator)

make sure you're in radians mode if that's what is being asked for