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November 1st, 2017, 12:17 PM   #1
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arctan(tan(5pi/8))

arctan(tan(5pi/8 ))

I got lost on this problem on an exam. I know by putting in a calculator that the solution is -3pi/8 but I had to show work. Could you guys explain the approach?
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November 1st, 2017, 12:27 PM   #2
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I know arctan means inverse. I’m just looking for direction on how you would show the work to solve for an exact solution.
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November 1st, 2017, 12:47 PM   #3
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Oh I get it now. It would be 5pi/8 because the arctan would cancel the tan but arctan is restricted to (-pi/2, pi/2) and since 5pi/8 is greater than pi/2 you find the equivalent angle within the restriction which is -3pi/8. Is this correct?
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November 1st, 2017, 12:50 PM   #4
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Quote:
Originally Posted by JPow View Post
Oh I get it now. It would be 5pi/8 because the arctan would cancel the tan but arctan is restricted to (-pi/2, pi/2) and since 5pi/8 is greater than pi/2 you find the equivalent angle within the restriction which is -3pi/8. Is this correct?
Yes.
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