(b)
Since, $|\overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}}|^{2} + |\overrightarrow{\mathbf{a}} \bullet \overrightarrow{\mathbf{b}}|^{2}$ =$\left| \overrightarrow{\mathbf{a}} \right|^{2}\ {|\overrightarrow{\mathbf{b}}|}^{2}$
$\Longrightarrow (10)^{2} + |\overrightarrow{\mathbf{a}} \bullet \overrightarrow{\mathbf{b}}|^{2} = (3)^{2} \bullet (4)^{2}$
$\Longrightarrow \ |\overrightarrow{\mathbf{a}} \bullet \overrightarrow{\mathbf{b}}|^{2} = 44$