Answer:
Part 1)
-----> 
Part 2)
---->
Part 3)
----> 
Part 4)
---> 
Step-by-step explanation:
we know that
In the unit circle
The coordinates of a point have the following rule

where
(x,y) are the coordinates of the point a r is the radius
but remember that in a unit circle the radius is equal to 1
so



<em><u>Find the x-coordinate of each case</u></em>
Part 1) we have the point

so
The y-coordinate is
Find the value of the x-coordinate
substitute



Part 2) we have the point

so
The y-coordinate is
Find the value of the x-coordinate
substitute



Part 3) we have the point

so
The y-coordinate is
Find the value of the x-coordinate
substitute



Part 4) we have the point

so
The y-coordinate is
Find the value of the x-coordinate
substitute


