SOLVING VOLUMES
USING CROSS
SECTIONAL AREAS
AP Calculus AB/ Christy Sohn (11)
Solving Volume of a Cross-Sectional
Solid

                          •Base: y      1 2
                                          x      2    x
   y                                    2
           1
       y     x2   2   x    •Cross Sectional Shapes:
           2
                                •Triangles perpendicular to the x-
                                axis.
                           •Interval: [0,4]
                      x
                          •Triangle Base: Triangle Height = 2:3
                               •Triangle Base= (2*(Triangle Height))/
                                                                   3
                                                     1               3
                          •Area of the Whole Triangle: ( Base * 2)(    )
                                                     2              4

                          •Function for Solving the Volume of the
                          Solid:     4
                                          3 1 2
                                            ( x        2 x ) 2 dx
                                     0
                                         3 2
Solutions
                                                       4
                                  Volume                   ( Area) dx
                                                       0

 y                                     4
                                            3 1 2
         1                                   ( x                 2     x ) 2 dx
     y     x2      2      x                3 2
         2                             0
                                            4        5
                                        3     1 4
                                          [( ( x 2 x 2 4 x)dx]
                                       3 0 4
                          x                                  7          4
                                        3 1 5          4
                                         ( x             x   2
                                                                     2x2 )
                                       3 20            7                0
                                                   7                                     7
                          3 1              4                    1                  4
                           [( (4) 5          (4)   2
                                                       2(4) ) ( (0) 5
                                                                 2
                                                                                     (0) 2   2(0) 2 )]
                         3 20              7                   20                  7

                 3 256    512                    3 5472                1824 3
                  (             32 )              (     )
                3 5        7                    3 35                       35
                                                                       90 .2646   90 .26

Solving volumes using cross sectional areas

  • 1.
    SOLVING VOLUMES USING CROSS SECTIONALAREAS AP Calculus AB/ Christy Sohn (11)
  • 2.
    Solving Volume ofa Cross-Sectional Solid •Base: y 1 2 x 2 x y 2 1 y x2 2 x •Cross Sectional Shapes: 2 •Triangles perpendicular to the x- axis. •Interval: [0,4] x •Triangle Base: Triangle Height = 2:3 •Triangle Base= (2*(Triangle Height))/ 3 1 3 •Area of the Whole Triangle: ( Base * 2)( ) 2 4 •Function for Solving the Volume of the Solid: 4 3 1 2 ( x 2 x ) 2 dx 0 3 2
  • 3.
    Solutions 4 Volume ( Area) dx 0 y 4 3 1 2 1 ( x 2 x ) 2 dx y x2 2 x 3 2 2 0 4 5 3 1 4 [( ( x 2 x 2 4 x)dx] 3 0 4 x 7 4 3 1 5 4 ( x x 2 2x2 ) 3 20 7 0 7 7 3 1 4 1 4 [( (4) 5 (4) 2 2(4) ) ( (0) 5 2 (0) 2 2(0) 2 )] 3 20 7 20 7 3 256 512 3 5472 1824 3 ( 32 ) ( ) 3 5 7 3 35 35 90 .2646 90 .26