a.docx

           a

                                   b                                                                        a                

                  P = a

b                                                                   P = a

           e

                                                                                                            h

                                     f                                                                     a                                                                                              

                P = ef                                                                 P = ah

                          2                                                                               

                                                                                                           b

                              h                                                               h 

                           a                                                                              a

             P = ah                                                           P = ( a + b )h

                        2                                                                             2