chapter 23 I still have thirteen solutions to this question (1)

He first looked at Nora Gu: “Nora Gu, have you found the solution?”
Nora Gu gently shook her head. The same problem had been written on the blackboard by Sean Xu the day before. She had pondered it all night long but still couldn't find a breakthrough in solving it.
Sean Xu didn’t react but then turned his attention to Brandon Ou.
“Brandon Ou, what about you?”
Brandon Ou also shook his head. This problem, which integrated trigonometric functions, geometric properties, and vectors,...