Answer:
x = -
Step-by-step explanation:
the equation of a circle centred at the origin is
x² + y² = r² ( r is the radius )
The radius of a unit circle is r = 1
substitute (x, - ) into the equation and solve for x
x² + (- )² = 1²
x² + = 1 ( subtract
from both sides )
x² = 1 - =
( take square root of both sides )
x = ± = ±
since the point is in the 3rd quadrant then x < 0
x = -