Question

The point P is on the unit circle. Find the y-coordinate of P if the x-coordinate is (-2/5) and P is above the x-axis.
A) 1/5
B) (radical 6)/5
C) (radical 21)/5
D) 3(radical 2)/5
E) 2/5

Answer 1

sqrt(1-(-2/5)^2)

Answer 2

sin(cos^-1(-2/5)) ?

Answer 3

sqrt(1 - 4/25) = sqrt(21/25) = sqrt(21)/5 c