Inverse function of elementary function

Exercise2.4
1. Show that $z^{1/2}$ has two branches.

2. Find all of the following values.

(a)
$\log{2}$
(b)
$\log{(-1)}$
(c)
$\log{i}$
(d)
$\log(1+i)$

3. Express the following value in the form of $a + bi$.

(a)
$(-1)^{i}$
(b)
$i^{i}$
(c)
$2^{i}$
(d)
$2^{1+i}$

4. Prove the following formulas.

(a)
$\sin^{-1}{z} = \frac{1}{i}\log{(iz \pm \sqrt{1 - z^2})}$
(b)
$\tan^{-1}{z} = \frac{1}{2i}\log{\frac{1 + iz}{1 - iz}}$

(5) Find the following values.

(a)
$\cos^{-1}{1}$
(b)
$\sin^{-1}{2}$
(c)
$\cos^{-1}{i}$