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# fp2 complex numbers question watch

1. For these type of problems, I thought the solutions of the argument needed to be within -pi to pi.

Why arent the values of theta: pi/10, pi/2, 9pi/10, -3pi/10 and -7pi/10 ?

Is the solution bank incorrect or am i wrong in thinking this solutions have to be in the range stated above?

thanks
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2. (Original post by Katiee224)
For these type of problems, I thought the solutions of the argument needed to be within -pi to pi.

Why arent the values of theta: pi/10, pi/2, 9pi/10, -3pi/10 and -7pi/10 ?

Is the solution bank incorrect or am i wrong in thinking this solutions have to be in the range stated above?

thanks
Both are right, just one is in a range of 0 to 2pi instead, if you multiply your last 2 values by e^(2ipi) = 1 you will get the last 2 values as written in the solution. Usually a question will tell you what the range is. If you draw an Argand diagram showing the solutions you'll see that -3pi/10 and 17pi/10 are the same, same for the other pair of solutions.
3. (Original post by __Adam__)
Both are right, just one is in a range of 0 to 2pi instead, if you multiply your last 2 values by e^(2ipi) = 1 you will get the last 2 values as written in the solution. Usually a question will tell you what the range is. If you draw an Argand diagram showing the solutions you'll see that -3pi/10 and 17pi/10 are the same, same for the other pair of solutions.
ohhh i see, thanks you

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