(19981998/19971997)-1的简便运算

来源:学生作业帮助网 编辑:作业帮 时间:2024/07/11 21:27:47
(19981998/19971997)-1的简便运算
x){9өk|Vu OumW_`gC-P *l$Epͺ ̂J@yvPـ9O?oQgh $ 43L  :5Cb4mf)!*``՚`Dz- 4ȶi06Є)҅25h Pި8ʁ)2ˁD`H:

(19981998/19971997)-1的简便运算
(19981998/19971997)-1的简便运算

(19981998/19971997)-1的简便运算
(19981998/19971997)-1
=(1998×10001/1997×10001)-1
=1998/1997-1997/1997
=1/1997

原式=(tan10-tan60)sin40
=(sin10/cos10-sin60/cos60)sin40
=sin40(sin10cos60-cos10sin60)/(cos10cos60)
=sin40*sin(10-60)/(sin80sin30))
=-sin40*sin50/(sin80sin30))
=-sin40cos40/(2sis40cos40sin30)
=-1/(2sin30)
=-1