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principal argZ1 = a and principal argZ2=b . what will be arguement of (Z1.Z2) when a+b is greater than pi.According to me it should be a+b-pi but its given a+b-2 pi .

Swati
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  • See the formula here: http://math.stackexchange.com/questions/138310/show-that-2-tan-12-pi-cos-1-frac35/583359#583359 OR in my answer here : http://math.stackexchange.com/questions/523625/showing-arctan-frac23-frac12-arctan-frac125 – lab bhattacharjee Jul 07 '15 at 08:49

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The argument is determined up to a multiple of $2\pi$, so if $a+b$ is too big, you have to subtract $2\pi$.

mrf
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  • but in my question they are saying that a+b is greater than pi. that means my angle is lying in third quadrant . so accordingly i'm supposed to write a+b- π. – Swati Jul 07 '15 at 09:06
  • Then $a+b-\pi$ is an angle in the first quadrant, so that can't be right. – mrf Jul 07 '15 at 09:11
  • can u please elaborate..? – Swati Jul 07 '15 at 09:16