Answer:
Attachment 1 : Option C
Attachment 2 : Option A
Step-by-step explanation:
( 1 ) Expressing the product of z1 and z2 would be as follows,
![14\left[\cos \left(\frac{\pi \:}{5}\right)+i\sin \left(\frac{\pi \:\:}{5}\right)\right]\cdot \:2\sqrt{2}\left[\cos \left(\frac{3\pi \:}{2}\right)+i\sin \left(\frac{3\pi \:\:}{2}\right)\right]](https://tex.z-dn.net/?f=14%5Cleft%5B%5Ccos%20%5Cleft%28%5Cfrac%7B%5Cpi%20%5C%3A%7D%7B5%7D%5Cright%29%2Bi%5Csin%20%5Cleft%28%5Cfrac%7B%5Cpi%20%5C%3A%5C%3A%7D%7B5%7D%5Cright%29%5Cright%5D%5Ccdot%20%5C%3A2%5Csqrt%7B2%7D%5Cleft%5B%5Ccos%20%5Cleft%28%5Cfrac%7B3%5Cpi%20%5C%3A%7D%7B2%7D%5Cright%29%2Bi%5Csin%20%5Cleft%28%5Cfrac%7B3%5Cpi%20%5C%3A%5C%3A%7D%7B2%7D%5Cright%29%5Cright%5D)
Now to solve such problems, you will need to know what cos(π / 5) is, sin(π / 5) etc. If you don't know their exact value, I would recommend you use a calculator,
cos(π / 5) =
,
sin(π / 5) = 
cos(3π / 2) = 0,
sin(3π / 2) = - 1
Let's substitute those values in our expression,
And now simplify the expression,

The exact value of
=
and
=
Therefore we have the expression
, which is close to option c. As you can see they approximated the solution.
( 2 ) Here we will apply the following trivial identities,
cos(π / 3) =
,
sin(π / 3) =
,
cos(- π / 6) =
,
sin(- π / 6) = 
Substitute into the following expression, representing the quotient of the given values of z1 and z2,
⇒
![15\left[\frac{1}{2}+\frac{\sqrt{3}}{2}\right]\div \:3\sqrt{2}\left[\frac{\sqrt{3}}{2}+-\frac{1}{2}\right]](https://tex.z-dn.net/?f=15%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%2B%5Cfrac%7B%5Csqrt%7B3%7D%7D%7B2%7D%5Cright%5D%5Cdiv%20%20%5C%3A3%5Csqrt%7B2%7D%5Cleft%5B%5Cfrac%7B%5Csqrt%7B3%7D%7D%7B2%7D%2B-%5Cfrac%7B1%7D%7B2%7D%5Cright%5D)
The simplified expression will be the following,
or in other words
or 
The solution will be option a, as you can see.