$$\text { Find the surface area generated by rotating the lemniscate } r ^ { 2 } = 10 \cos 2 \theta \text { about the line } \theta = \pi \text {. }$$

Short Answer

$$\text { Find the surface area generated by rotating the lemniscate } r ^ { 2 } = 10 \cos 2 \theta \text { about the line } \theta = \pi \text {. }$$