How do you simplify complex number?

#((1-isqrt3)(cosvarphi+isinvarphi))/(2(1-i)(cosvarphi-isinvarphi))#

Answer: #sqrt2/2(cos(2varphi-pi/12)+isin(2varphi-pi/12))#

1 Answer
Dec 27, 2017

Given:

#((1-isqrt3)(cos(varphi)+isin(varphi)))/(2(1-i)(cos(varphi)-isin(varphi)))#

Using Euler's formula #e^(ivarphi)=cos(varphi)+isin(varphi)# and #e^(-ivarphi)=cos(varphi)-isin(varphi)#

#((1-isqrt3)(cos(varphi)+isin(varphi)))/(2(1-i)(cos(varphi)-isin(varphi)))= ((1-isqrt3)(e^(i(varphi))))/(2(1-i)(e^(-i(varphi))))#

Division of exponential function is the same as subtracting the exponents:

#((1-isqrt3)(e^(i(varphi))))/(2(1-i)(e^(-i(varphi)))) = ((1-isqrt3)(e^(i(varphi- -varphi))))/(2(1-i))= #

#((1-isqrt3)(e^(i(2varphi))))/(2(1-i))#

Convert #(1-isqrt3)# to #Ae^(itheta)# form:

#A = sqrt(1^2+(-sqrt3)^2) = 2# and #theta = tan^-1(-sqrt3/1)= -pi/3#

#((1-isqrt3)(e^(i(2varphi))))/(2(1-i)) = (2e^(-ipi/3)(e^(i(2varphi))))/(2(1-i))#

#2/2 to 1#:

#(2e^(-ipi/3)(e^(i(2varphi))))/(2(1-i)) = (e^(-ipi/3)(e^(i(2varphi))))/((1-i))#

Convert #(1-i)# to #Ae^(itheta)# form:

#A = sqrt(1^2+(-1)^2)= sqrt2# and #theta = tan^-1(-1/1) = -pi/4#

#(e^(-ipi/3)(e^(i(2varphi))))/((1-i))= (e^(-ipi/3)(e^(i(2varphi))))/(sqrt2e^(i(-pi/4)))#

Combine the exponents:

#(e^(-ipi/3)(e^(i(2varphi))))/(sqrt2e^(i(-pi/4)))=(e^(i(2varphi-pi/12)))/sqrt2#

Rationalize the denominator:

#(e^(i(2varphi-pi/12)))/sqrt2 = sqrt2/2e^(i(2varphi-pi/12))#

Use Euler's formula:

#sqrt2/2e^(i(2varphi-pi/12)) = sqrt2/2(cos(2varphi-pi/12)+isin(2varphi-pi/12))#