Using the unit circle, it is found that the value of y is given by:
[tex]x^2 + y^2 = 1[/tex]
At point P, we have that [tex]x = \frac{2}{5}[/tex], and hence, we have to find the value of y.
[tex]x^2 + y^2 = 1[/tex]
[tex]\left(\frac{2}{5}\right)^2 + y^2 = 1[/tex]
[tex]\frac{4}{25} + y^2 = 1[/tex]
[tex]y^2 = 1 - \frac{4}{25}[/tex]
[tex]y^2 = \frac{21}{25}[/tex]
[tex]y = \pm \sqrt{\frac{21}{25}}[/tex]
[tex]y = \pm \frac{\sqrt{21}}{5}[/tex]
To learn more about the unit circle, you can take a look at https://brainly.com/question/16852127
