这个式子是什么?怎么证明?

2个回答

  • 用数学归纳法证明.

    证明:

    当n=1时,(cosπ/6+isinπ/6)^1=cos(π/6)+i sin( π/6)显然成立

    假设n=k,(cosπ/6+isinπ/6)^k=cos(kπ/6)+i *sin( kπ/6)成立,

    当n=k+1时,(cosπ/6+isinπ/6)^(k+1)

    =(cosπ/6+isinπ/6)^k*(cosπ/6+isinπ/6)

    =(coskπ/6+isin kπ/6)*(cosπ/6+isinπ/6)

    =coskπ/6*cosπ/6-sinkπ/6sinπ/6+i(sinπ/6coskπ/6+sinkπ/6cosπ/6)

    =cos[(k+1)π/6]+isin[(k+1)π/6]

    证毕.

    望采纳谢谢~~