Find the area of the smaller part of the circle $x^2 + y^2 = a^2$ cut off by the line $x =\Large { \frac{a}{\sqrt 2}}$.

Question

$\begin{array}{1 1} \large \frac{a^2}{2}\begin{bmatrix}\frac{\pi}{2}-1\end{bmatrix}sq.units. \\\large \frac{a^3}{3}\begin{bmatrix}\frac{\pi}{2}-1\end{bmatrix}sq.units . \\ \large \frac{a^2}{2}\begin{bmatrix}\frac{\pi}{4}-1\end{bmatrix}sq.units. \\ \large \frac{a^2}{2}\begin{bmatrix}\frac{\pi}{\sqrt 2}-1\end{bmatrix}sq.units. \end{array} $