How do you evaluate e^( ( 13 pi)/8 i) - e^( ( pi)/2 i)e13π8ieπ2i using trigonometric functions?

1 Answer
Apr 11, 2016

e^((13pi)/8i) - e^(pi/2i) = 0.383 - 1.924ie13π8ieπ2i=0.3831.924i

Explanation:

According to Euler's formula,

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

Using values for xx from the equation, (13pi)/813π8 and pi/2π2

x = (13pi)/8x=13π8
e^((13pi)/8i) = cos((13pi)/8) + isin((13pi)/8)e13π8i=cos(13π8)+isin(13π8)
= cos292.5 + isin292.5=cos292.5+isin292.5
= 0.383 - 0.924i=0.3830.924i

x = pi/2x=π2
e^(pi/2i) = cos(pi/2) + isin(pi/2)eπ2i=cos(π2)+isin(π2)
= cos90 + isin90=cos90+isin90
= i=i

Inserting these two values back into the original question,

e^((13pi)/8i) - e^(pi/2i) = 0.383 - 0.924i - ie13π8ieπ2i=0.3830.924ii
= 0.383 - 1.924i=0.3831.924i