In the diagram, $O$ is the center of a circle with radius 6 cm. Arc $JK$ has a length measuring 2\pi  cm. Determine the exact area of sector $OJK$.
Please directly answer the question and provide the final value, e.g., 1, 2.5, 300.
Question: In the diagram, $O$ is the center of a circle with radius 6 cm. Arc $JK$ has a length measuring 2\pi  cm. Determine the exact area of sector $OJK$.
Please first conduct reasoning, and then answer the question and provide the final value, e.g., 1, 2.5, 300, at the end.
Question: In the diagram, $O$ is the center of a circle with radius 6 cm. Arc $JK$ has a length measuring 2\pi  cm. Determine the exact area of sector $OJK$.