┌─────────────────┐
╭ 1  │       2        2        ╭ 1
|   ⟍│(dx/dt) +(dy/dt)   dt =  |   f(t) dt  ≃ ┌ \underset strip 1 \underbrace C   · f(t )   + ...  + \underset strip n \underbrace C   · f(t )  ┐ =
╯ -1                           ╯ -1           └                                1       1                                            n       n   ┘
                                                                                    __ n
                                           \underset strips 1 through n \underbrace ❯      C   · f(t )   
                                                                                    ‾‾ i=1  i       i