Question

If the point P(-3/5,y) lies on the unit circle and p is in the third quadrant, what is the value of y?

Answer 1

y = -4/5

Explanation:

Answer 2

Since
`P` lies in the third quadrant,
`y` must be negative. Also, because
`P` lies on the unit circle, its coordinates must satsify


`\left(-\frac35\right)^2+y^2=1\implies y^2=(16)/(25)\implies y=\pm\frac45`

Take the negative root, since
`y<0`, so that
`y=-\frac45`.