Page 234 - Calculus Demystified
P. 234

Applications of the Integral
                     CHAPTER 8
















                                                     Fig. 8.7                                    221





                                                                    √3
                                                                    2
                                              b           b           b



                                                    b
                                                     Fig. 8.8

                         triangular slice at position x has area
                                             √
                                               3  	         
 2  √       2
                                      A(x) =     · 2 1 − x 2  =   3(1 − x ).
                                              4
                         Finally, we may conclude that the volume we seek is
                                              1

                                       V =      A(x) dx
                                             −1

                                              1 √
                                                        2
                                          =       3(1 − x )dx
                                             −1
                                                         1
                                            √        x 3
                                          =   3 x −
                                                     3  −1

                                            √         1             −1
                                          =   3   1 −    − (−1) −
                                                      3              3
                                             √
                                            4 3
                                          =      .
                                              3
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