Extra Credits

(chx)^2=(shx)^2+ 1；

ch(x+y)=chx * chy + shx * shy

Ch (2x) = (CHX) 2+(SHX) 2 = 2 * (SHX) 2+1= 2 * (CHX) 2-1

Including the formula of power up and power down (corresponding to the last two equal signs)

similar

sh(x+y)= CHX * shy+chy * shx；

So sh (2x) = 2 * CHX * SHX;

Well, that's almost enough. You can use it. Give me extra points. I think it is the first Chinese Nobel Prize winner in Mathematics (haha).

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