How do you evaluate e^( (3 pi)/2 i) - e^( ( 5 pi)/8 i)e3π2ie5π8i using trigonometric functions?

1 Answer
Apr 8, 2016

0.157 + 0.386i0.157+0.386i

Explanation:

According to Euler's formula,

e^(ix) = cosx + isinxeix=cosx+isinx.

Inserting values for x = (3pi)/2x=3π2 and (5pi)/85π8,

e^((3pi)/2i) = cos((3pi)/2) + isin((3pi)/2)e3π2i=cos(3π2)+isin(3π2)
= cos270 + isin270=cos270+isin270
= 0.984 - 0.176i=0.9840.176i

e^((5pi)/8i) = cos((5pi)/8) + isin((5pi)/8)e5π8i=cos(5π8)+isin(5π8)
= cos112.5 + isin112.5=cos112.5+isin112.5
= 0.827 - 0.562i=0.8270.562i

Putting both of these together,

e^((3pi)/2i) - e^((5pi)/8i) = 0.984 - 0.827 - 0.176i + 0.562ie3π2ie5π8i=0.9840.8270.176i+0.562i
= 0.157 + 0.386i=0.157+0.386i