Question

if the point P(-3/5,y)lies on the unit circle and P is in the second quadrant, what does y equal

Answer 1

If  P(x, y)  lies on the unit circle, then the distance from  P  to the origin must be  1:

     √(x² + y²) = 1

     x² + y² = 1

     (– 3/5)² + y² = 1

     (9/25) + y² = 1


Multiply both sides by  25:

     9 + 25y² = 25


Solve the equation for  y:

     25y² = 25 – 9

     25y² = 16

     y² = 16/25

     y² = (4/5)²


Take the square root of both sides:

     y = ± √(4/5)²

     y = ± 4/5


Since  P  is in the second quadrant, then  y  must be positive:

     y > 0


So,

     y = 4/5   <———   this is the answer.


I hope this helps. =)

Answer 2

Answer:

Y=4/5

Step-by-step explanation:

This is a 3, 4, 5 right triangle, and since it is isn’t he second quadrant x is negative but y is positive.