diff --git a/sin x = 2.md b/sin x = 2.md index ddd484e..db9c717 100644 --- a/sin x = 2.md +++ b/sin x = 2.md @@ -19,22 +19,40 @@ $$ u - u^{-1} = 4i $$ $$ -u^2 - 1 = 4iu \\ $$$$ +u^2 - 1 = 4iu \\ $$ +$$ u^2 - 4iu - 1 = 0 -$$$$ -u^2 - 4iu - 4 = -3 $$$$ -(u - 2i)^2 = -3 \\ $$$$ -u - 2i = \pm \sqrt {-3} $$$$ -u = 2i \pm \sqrt {-3} \\ $$$$ +$$ +$$ +u^2 - 4iu - 4 = -3 +$$ +$$ +(u - 2i)^2 = -3 \\ +$$ +$$ +u - 2i = \pm \sqrt {-3} +$$ +$$ +u = 2i \pm \sqrt {-3} \\ +$$ +$$ u = i(2 \pm \sqrt 3) $$ Substitute back into $u$, for $n \in \mathbb{Z}$: $$ -e^{ix} = i(2 \pm \sqrt 3) \\ $$$$ -ix = \ln (i(2 \pm \sqrt 3)) \\ $$$$ -ix = \ln i + 2\pi n+ \ln(2 \pm \sqrt 3) \\ $$$$ -ix = \frac {i\pi} 2 + 2\pi n + \ln(2 \pm \sqrt 3) $$$$ +e^{ix} = i(2 \pm \sqrt 3) \\ +$$ +$$ +ix = \ln (i(2 \pm \sqrt 3)) \\ +$$ +$$ +ix = \ln i + 2\pi n+ \ln(2 \pm \sqrt 3) \\ +$$ +$$ +ix = \frac {i\pi} 2 + 2\pi n + \ln(2 \pm \sqrt 3) +$$ +$$ x = \frac \pi 2 - i\ln(2 \pm \sqrt 3) + 2\pi n $$