I assume that by log( ) you mean loge( ) and not 
log10( ) as most people in the US mean by log( ).  
When we want to indicate loge we write ln( ). If
you meant log10 then tell me in the thank-you note 
form below and I'll get back to you. 
Use Euler's equation:
         

 ,
Substitute ln(1+i) for a+bi on the left
,
Substitute ln(1+i) for a+bi on the left 
         

 
         

 eq. 1
eq. 1    

 Set the real part on the left side of eq. 1 
equal to the real part on the right of eq. 1:
eq. 2
Set the real part on the left side of eq. 1 
equal to the real part on the right of eq. 1:
eq. 2    

 Set the imaginary part on the left side of eq. 1 
equal to the imaginary part on the right of eq. 1:
eq. 3
Set the imaginary part on the left side of eq. 1 
equal to the imaginary part on the right of eq. 1:
eq. 3    

 Divide equals by equals, that is, divide both side 
of eq. 2 by both sides of eq. 1
Divide equals by equals, that is, divide both side 
of eq. 2 by both sides of eq. 1




 


 The tangent is positive in QI and QIII so
The tangent is positive in QI and QIII so


 However in eq. 3
However in eq. 3


 ,
the left side is positive, and ea is positive,
so we can discard the QIII answer. 
Substitute in eq. 3, using
,
the left side is positive, and ea is positive,
so we can discard the QIII answer. 
Substitute in eq. 3, using 

 


 


 


 


 


 


 


 


 Square both sides to eliminate the square root:
Square both sides to eliminate the square root:


 


 Take ln of both sides:
Take ln of both sides:


 


 


 So the solution is
So the solution is


 Edwin
Edwin