Using a calculator to find values of definite integrals and to graph indefinite integrals. (TI-82/83)

General method: Most graphing calculator models have built-in functions that calculate numerical approximations of integrals

Example: To evaluate [Maple Math]

enter fnInt(sin(X),X,0,2)

To graph [Maple Math] insert fnInt(sin(T),T,0,X) as Y1 in the "Y=" menu and graph the result.

Notes: The fnInt command is found in the MATH menu as item number 9.

As demonstrated above, fnInt has four required arguments. Listed in order, they are the function to be integrated, the variable of integration, the lower limit of integration, and the upper limit of integration. There is a fifth optional argument which indicated a tolerance for the computation. Very small values give lots of accuracy but slow calculation. Larger values give less accuracy but compute the result more quickly. For example, you might enter fnInt(sin(X),X,0,2,0.0001). If you do not supply a tolerance, the calculator will use 0.00001. For the graphing suggested above, it is wise to use a large tolerance such as 0.01.



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