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## Main Question or Discussion Point

I know all the well know angles from 0 to [tex] \pi/2[/tex]. However, past pi/2 I am rather clueless and have no idea what angle corresponds to what value.

For example, in trying to figure out [tex] tan^{-1}(-1)[/tex] How does one know it is 5pi/4 and not 7pi/8? I was debating between measuring pi/4 from the negative x axis (which would give me 7pi/8) and measuring pi/4 from the y axis,(which would give me 5pi/4) but as you can see, I choose the wrong value. Is there a trick to it? Thanks.

For example, in trying to figure out [tex] tan^{-1}(-1)[/tex] How does one know it is 5pi/4 and not 7pi/8? I was debating between measuring pi/4 from the negative x axis (which would give me 7pi/8) and measuring pi/4 from the y axis,(which would give me 5pi/4) but as you can see, I choose the wrong value. Is there a trick to it? Thanks.