# Find the principal argument and exponential form of z=i/(1+i) If z=x+iy is a complex number

Question
Complex numbers
Find the principal argument and exponential form of $$\displaystyle{z}=\frac{{i}}{{{1}+{i}}}$$ If z=x+iy is a complex number

2020-11-02
Rewrite the above complex number in the usual form z=x+iy as follows.
$$\displaystyle{z}=\frac{{i}}{{{1}+{i}}}=\frac{{i}}{{{1}+{i}}}\cdot\frac{{{1}-{i}}}{{{1}-{i}}}$$ [multiply and divide by the conjugate 1−i of 1+i]
$$\displaystyle=\frac{{{i}{\left({1}-{i}\right)}}}{{{\left({1}+{i}\right)}{\left({1}-{i}\right)}}}=\frac{{{i}-{i}^{{2}}}}{{{1}^{{2}}-{i}^{{2}}}}={\left({i}+{1}\right)}{\left({1}+{1}\right)}=\frac{{{i}+{1}}}{{2}}=\frac{{1}}{{2}}+\frac{{1}}{{2}}{i}$$
Compare the complex number $$\displaystyle{z}=\frac{{1}}{{2}}+\frac{{1}}{{2}}{i}$$ with z=x+iy and obtain $$\displaystyle{x}=\frac{{1}}{{2}}$$ and $$\displaystyle{y}=\frac{{1}}{{2}}.$$
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