Answer:
and
.
Step-by-step explanation:
The equation can be simplified with the help of trigonometric identities:

Which means that equation is equal to zero if any component of the product is zero. The solutions of the expression are:
a) 

b) 



Any value different of both subsets do not satisfy the equation described above.
Step-by-step explanation:
Hey there!
f(x) = 7/x
<em>~ Simply keep the "7" in the place where "x" is there.</em>

Therefore, X= 1.
<em><u>Hope</u></em><em><u> it</u></em><em><u> helps</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em>
I believe it's b , hopefully this helps