Using a calculator to find values of definite integrals and to graph indefinite integrals. (TI-85/86)

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 CALC menu.

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. During the computation, the calculator uses an additional numerical parameter called the "tolerance" to determine the accuracy of the result. Very small values give lots of accuracy but slow calculation. Larger values give less accuracy but compute the result more quickly. You can adjust the tolerance in the MEM/TOL menu. For the graphing suggested above, it is wise to use a large tolerance such as 0.01.



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