Exercise 2.  Establish the following identities.

2 (g).   [Graphics:Images/ComplexFunTrigInverseModHome_gr_431.gif].

Solution 2 (g).

Solution.   Start with  [Graphics:../Images/ComplexFunTrigInverseModHome_gr_432.gif]  and obtain   [Graphics:../Images/ComplexFunTrigInverseModHome_gr_433.gif].   

This gives  [Graphics:../Images/ComplexFunTrigInverseModHome_gr_434.gif].   Multiplying by  [Graphics:../Images/ComplexFunTrigInverseModHome_gr_435.gif]  results in   [Graphics:../Images/ComplexFunTrigInverseModHome_gr_436.gif].  

Use the quadratic formula to solve for  [Graphics:../Images/ComplexFunTrigInverseModHome_gr_437.gif]  and obtain  

                    [Graphics:../Images/ComplexFunTrigInverseModHome_gr_438.gif],  

where the fractional power is the multivalued square root function.   

Taking the multivalued log of both sides gives the desired result:

                    [Graphics:../Images/ComplexFunTrigInverseModHome_gr_439.gif].

Therefore,   [Graphics:../Images/ComplexFunTrigInverseModHome_gr_440.gif].   

We are done.   

Aside.  The principal value of  [Graphics:../Images/ComplexFunTrigInverseModHome_gr_441.gif]  can be calculated with Mathematica.

[Graphics:../Images/ComplexFunTrigInverseModHome_gr_442.gif]

[Graphics:../Images/ComplexFunTrigInverseModHome_gr_443.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2008 John H. Mathews, Russell W. Howell