Three Basic Substitutions
Inverses

Trigonometric Substitutions
Trigonometric substitutions replace the binomials
,
,

by single squared terms, so square roots can be simplified and integrals
can be evaluated directly.

Three Basic Substitutions


                            


                          


                         

The substitutions replaces a function of    by a function of .
In order to get the answer to the integral problem back in terms of  ,
we need the above trigonometric substitutions to be reversible.
The substitutions must have inverses.
The inverses exist under the following conditions:

    requires
                                         

   requires
                                         

   requires
                                        
                                                                           .


See Examples 1 - 4, pages 566 - 569.


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