precal question

Question

The point P is on the unit circle. Find P(x, y) from the given information.

The x-coordinate of P is − 13/4

,

 and P lies below the x-axis.

P(x, y) =

 

 

Answer 1

Since P = (x,y) lies below the x-axis and since P is on the unit circle, y < 0 and x² + y² = 1.

Since x = -√13 / 4, we have (13/16) + y² = 1. So, y² = 3/16. Therefore, y = -√3 /4.