If the point P(-4/5,y) lies on the unit circle and P is in the third quadrant, what does y equal?

1. If the point P(-4/5,y) lies on the unit circle and P is in the third quadrant, what does y equal?

2. There are values of t so that sin t = .3 and cos t = -.6.

Is this statement true or false???

Thank you!

1)

16/25 + y^2 = 1

y^2 = 9/25

y = -3/5

2)

sin^2 t + cos^2 t = 0.3^2 + 0.6^2 = 0.45

this must equal 1 so this statement is false.
equation for unit circle is: x^2 + y^2 = 1

substituting the given x coord in this equation: y = +/- sqrt(1 – (-4/5)^2) = +/- 3/5