New transfer student Su Wanyin formed a paper connection with Class A genius Lu Yanshen because of a trigonometric function problem. She solved the questions and he answered them. After she got a perfect score in the monthly exam, he added her on WeChat and said, "I'll treat you to a meal." At the same time, Xie Lansheng from Class B recognized her - the third place in the national mathematics competition last year. Three functional curve-like thoughts began to intertwine in this September. A campus story about trigonometric functions, about heartbeat, and about chasing answers.
Idea: Sine and cosine always differ by one quarter period