How do you evaluate e^( ( pi)/4 i) - e^( ( 7 pi)/3 i)eπ4ie7π3i using trigonometric functions?

1 Answer
Jul 13, 2018

Euler's Formula states that

e^(icolor(red)theta) = coscolor(red)theta+isincolor(red)thetaeiθ=cosθ+isinθ

Which is the trigonometric form of a complex number. Hence,

e^(icolor(red)(pi/4))=cos(color(red)(pi/4)) +isin(color(red)(pi/4))=sqrt2/2+isqrt2/2eiπ4=cos(π4)+isin(π4)=22+i22

e^(icolor(red)((7pi)/3))=cos(color(red)((7pi)/3)) + isin(color(red)((7pi)/3))ei7π3=cos(7π3)+isin(7π3)
=cos(2pi+pi/3)+isin(2pi+pi/3)=cos(2π+π3)+isin(2π+π3)
=cos(pi/3) + i sin(pi/3)=cos(π3)+isin(π3)
=1/2+isqrt3/2=12+i32

:. e^(ipi/4) - e^(i(7pi)/3)=sqrt2/2+isqrt2/2-1/2-isqrt3/2

=(sqrt2/2-1/2)+i(sqrt2/2-sqrt3/2)