the given example in the book states the argument of z=4+4i.

1. it has said to use $\displaystyle tan=\frac{4}{4}=1$

2. then it saids that the $\displaystyle arg(z)=\frac{\pi}{4}$

-my concern is, how did it get $\displaystyle arg(z)=\frac{\pi}{4}$ ?