(1+sin92π−icos92π1+sin92π+icos92π)3
=(1+cos185π−isin185π1+cos185π+isin185π)3=(2cos2365π−i2sin365π⋅cos365π2cos2365π+i2sin365π⋅cos365π)3
=(cos365π−isin365πcos365π+isin365π)3=(cos365π+isin365π)6
=cos(6×365π)+isin(6×365π)=cos65π+isin65π
=−23+i21