What are the coordinates of the point that corresponds to -7x/4 on the unit circle

This is a problem of intersection. So, we have two equations, first of all we have a straight line and the second equation is a circle with ratio equal to 1. Therefore, in a mathematical language this is established as follows:

(1)
(2)

We introduce (1) into (2):





There are two values, namely:



Then, substituing these values in the first (1) equation, we find:



Finally, the points are two: