$\frac{\cos{\left ( 45 ° + A \right )} + \cos{\left ( 45 ° - A \right )}}{\cos{\left ( 45 ° - A \right )} - \cos{\left ( 45 ° + A \right )}}$

=কত?

$\begin{aligned} & \frac{\cos \left(45^{\circ}+A\right)+\cos \left(45^{\circ}-A\right)}{\cos \left(45^{\circ}-A\right)-\cos \left(45^{\circ}+A\right)} \\ = & \frac{2 \cdot \cos 45^{\circ} \cdot \cos A}{2 \cdot \sin 45^{\circ} \cdot \sin A} \\ = & \frac{\cos A}{\sin A}=\cot A \text { } \end{aligned}$