How do you multiply e^(( 7 pi )/ 4 i) * e^( 3 pi/2 i ) e7π4ie3π2i in trigonometric form?

1 Answer
Mar 2, 2016

e^(7pi/4i)=(cos(7pi/4)+isin(7pi/4))=1/sqrt2-i(1/sqrt2)e7π4i=(cos(7π4)+isin(7π4))=12i(12)

e^(3pi/2i)=(cos(3pi/2)+isin(3pi/2))=-ie3π2i=(cos(3π2)+isin(3π2))=i.

Explanation:

Trigonometric form of e^(7pi/4i)e7π4i can be written as

(cos(7pi/4)+isin(7pi/4))(cos(7π4)+isin(7π4))

As cos(7pi/4)=cos(-pi/4)=cos(pi/4)=1/sqrt2cos(7π4)=cos(π4)=cos(π4)=12 and sin(7pi/4)=sin(-pi/4)=sin(pi/4)=-1/sqrt2sin(7π4)=sin(π4)=sin(π4)=12

e^(7pi/4i)e7π4i can be written as 1/sqrt2-i(1/sqrt2)12i(12)

and that of e^(3pi/2i)e3π2i can be written as

(cos(3pi/2)+isin(3pi/2))(cos(3π2)+isin(3π2)) and as cos(3pi/2)=0cos(3π2)=0 and sin(pi/2)=-1sin(π2)=1,

e^(3pi/2i)e3π2i can be written as -ii