The approximate area under the curve is found by adding the area of all the trapezoids.
(Recall that we write "Δx" to mean "a small change in x".)
A method for approximating a definite integral  using linear approximations of f. The trapezoids are drawn as shown below. The bases are vertical lines.
 using linear approximations of f. The trapezoids are drawn as shown below. The bases are vertical lines.
To use the trapezoid rule follow these two steps:
   
                           
 
   
 
 
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