9sin92/2cos46 * cos136
9sin92°/(2cos46° *cos136°)=9sin92°/(2cos46° *cos(90°+46°))= =9sin92°/(2cos46° *(-sin46°))=9sin92°/(-2sin46° *cos46°)= =9sin92°/(-sin(2*46°))=9sin92°/(-sin92°)=-9