Answer
$P\Big(-\dfrac{2}{5},\dfrac{\sqrt{21}}{5}\Big)$
Work Step by Step
The $x$-coordinate of $P$ is $-\dfrac{2}{5}$, and $P$ lies above the $x$-axis
Substitute $x$ by $-\dfrac{2}{5}$ into the equation of the unit circle:
$x^{2}+y^{2}=1$
$\Big(-\dfrac{2}{5}\Big)^{2}+y^{2}=1$
Solve for $y$:
$\dfrac{4}{25}+y^{2}=1$
$y^{2}=1-\dfrac{4}{25}$
$y^{2}=\dfrac{21}{25}$
$\sqrt{y^{2}}=\sqrt{\dfrac{21}{25}}$
$y=\pm\dfrac{\sqrt{21}}{5}$
Since $P$ lies above the $x$-axis, $y$ must be positive. The point $P$ is:
$P\Big(-\dfrac{2}{5},\dfrac{\sqrt{21}}{5}\Big)$
