cosr=l t 4 2K +2-…+(-1x 2!4! (2k) sin[5+(k+1)xt 2k+2 十 (2k+2) 2 4 coSx=1十 +(-1)42 2k+1 +0(x 2!4! (2k)! In(1+x=x +2+“+(+ n+1 +(-1) (n+1(1+5)”+1 2 x In(1+x)=x 十 +…+(-1) +0(x") 2021/2/20 232021/2/20 6 2 2 2 4 2 (2 2)! sin[ ( 1) ] (2 )! ( 1) 2! 4! cos 1 + + + + + = − + − + − k k k x k k k x x x x    ( ) (2 )! ( 1) 2! 4! cos 1 2 1 2 4 2 + = − + − + − + k k k o x k x x x x  n x x x x x n n 1 2 3 ( 1) 2 3 ln(1 ) − + = − + ++ − 1 1 ( 1)(1 ) ( 1) + + + + + − n n n n x  ( 1) ( ) 2 3 ln(1 ) 1 2 3 n n n o x n x x x + x = x − + + + − +  −