Find the determinant of the $n\times n$ matrix
$\begin{bmatrix} 2cos\Theta & 1 & 0 &0 &........ & 0 & \\ 1&2cos\Theta &1 & 0 & ........ & 0 & \\ 0&1 & 2cos\Theta & 1 &........ & 0 & \\ ....&.... &... &.... & .... & ...& \\ 0&.... & .... &.... & 1 & 2cos\Theta & \end{bmatrix}$
how the answer could be $D_{n}-2cos\Theta D_{n-1}+D_{n-2}=0$?
Plz explain