I Open a Historical IF Line in a Different World

Five hundred years after becoming a great sage from another world, Yu Xian decided to do something for his hometown in China. A year later, the first and possibly only historical if line in another world officially opened for business If Liu Ju becomes Fusu, can he lead an army of 300,000 to conquer the Central Plains? If Han Xin chooses to stand on his own, will Chu and Han evolve into the Three Kingdoms? If Huo Qubing lived a long life, how big could the territory of the Western Han Dynasty be? If Zhuge Liang succeeded in extending his life, maybe there wouldn't be three families returning to Jin? If Li Longji died early, would the Anshi Rebellion still break out? If Liu Chan traveled through time and became Zhao Gou, would Yue Fei's Northern Expedition succeed? If Zhu Yunwen chooses to slowly reduce the vassal status, the problem of vassal kings in the Ming Dynasty may be gradually improved. If Wan Zhen'er had a son, the events of Emperor Jiajing and Daliyi would not have happened. If………… As for some historical anecdotes caused by this incident, that is another story. Note: 1. The male protagonist intervenes in history only to repair some of the regrets of history or to explore another possibility for the direction of historical development; 2. The name of the male protagonist Cosine is not only "salted fish" in reverse, but also a play on "odd changes to even and remains the same, symbols look at the quadrants" ("Change from odd to even remains unchanged, look at the quadrants for symbols" was originally a trigonometric formula for finding sine, cosine and cotangent). 3. The history generated by the IF line is a parallel space and will not affect the official history; 4. The tentative if lines include Qin (Liu Ju crossed over and became Fusu), Han (Han Xin was not killed, Huo Qubing lived a long life), Three Kingdoms (Zhuge Liang succeeded in extending his life), Tang (Li Longji died early), Song (Liu Chan crossed over and became Zhao Gou), Ming (Zhu Yunwen did not radically cut down the vassal, Wan Zhen'er had a son), etc. Purpose: Repair historical regrets