3÷(cosπ/3+isinπ/3)
=3/(1/2 + √3i/2 )
=3(1/2 -√3i/2 )/(1/2 + √3i/2 )(1/2 -√3i/2 ) (分母有理化)
=3(1/2 -√3i/2 )/(1/4+3/4)
=3(1/2 -√3i/2 )
=3/2-3√3i/2
找个纸抄下来看就容易多了