$\mathbf{A}+\mathbf{B}+\mathbf{C}=\pi$ হলে, $\cos ^{2} A+\cos ^{2} B+\cos ^{2} C=?$

$1+2 \cos A \cos B \cos C$

$1+\cos A \cos B \cos C$

$1-\cos A \cos B \cos C$

$1-2 \cos A \cos B \cos C$