How do you evaluate e15π8ie11π6i using trigonometric functions?

1 Answer
Mar 28, 2016

e15π8ie11π6i=1.7899+0.8827i

Explanation:

As eiθ=cosθ+isinθ, we have

e15π8i=cos(15π8)+isin(15π8)

= cos(ππ8)+isin(ππ8)

= cos(π8)+isin(π8)=0.9239+0.3827i

e11π6i=cos(11π6)+isin(11π6)

= cos(2ππ6)+isin(2ππ6)

= cos(π6)isin(π6)

= 32i12=0.86600.5i

Hence e15π8ie11π6i=(0.9239+0.3827i)(0.86600.5i)

= (0.92390.8660)+i(0.3827+0.5)

= 1.7899+0.8827i