Answer
$\dfrac{\sqrt 2}{2}$
Work Step by Step
Rationalize the denominator by multiplying $\sqrt2$ to both the numerator and the denominator:
$\dfrac{1}{\sqrt 2}=\dfrac{1}{\sqrt 2} \cdot \dfrac{\sqrt 2}{\sqrt 2}$
Simplify.
$=\dfrac{\sqrt 2}{(\sqrt 2)^2}$
$=\dfrac{\sqrt 2}{2}$
Hence, the correct answer is $\frac{\sqrt 2}{2}$.
