Ti-89 Differing Answers from Integration

In summary, the conversation discusses a problem with solving an integral on a ti-89 calculator. The integral involves trigonometric functions and the values of r and a. When the integral is solved in degrees, the calculator gives an incorrect answer. However, when the integral is solved in radians, the correct answer is obtained. The reason for this difference is due to the calculator being set in degrees, and when the integral is converted to radians, the correct answer is obtained.
  • #1
jpreher
8
0
I am running into an interesting problem on my ti-89 and was wondering if anyone could explain the reason for the following.

I am attempting to solve the following:
[tex] M=\int_{x}^{y}sin(\theta )*(r-a*cos(\theta ))d\theta [/tex]

r = 0.14
a = 0.09

where,
x = 0 deg
y = 120 deg

The calculator gives me an answer of
[tex] M = 10.09838 [/tex]
This answer is incorrect, so I verified that the ti-89 was in degrees (it was) and decided to try the problem in rads instead to see if it is still incorrect.

now where,
x = 0 rad
y = 2*pi/3

I get a correct answer of
[tex] M = 0.17625 [/tex]

What is going on here?
 
Last edited:
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  • #2
your integral as written is radian based.
take your 10. 098 answer and divide by 57 degrees (1 rad) and you would get the second answer
 

Related to Ti-89 Differing Answers from Integration

1. Why does my Ti-89 calculator give me different answers for integration compared to other calculators?

The Ti-89 calculator uses a different algorithm for integration than other calculators, which can lead to slightly different results. It also has a more powerful processor, allowing it to handle more complex integrals that other calculators may struggle with.

2. How can I ensure that my Ti-89 integration results are accurate?

To ensure accuracy, it is important to use the correct syntax and parentheses when entering the integral into the calculator. It is also helpful to check the answer using an online calculator or by hand to compare results.

3. Why do I sometimes get an error message when trying to integrate on my Ti-89?

This can happen if the integral is too complex for the calculator to handle, or if there is a syntax error in the input. It is also possible that the calculator does not have enough memory to process the integral.

4. Can I change the integration settings on my Ti-89 to get more accurate results?

Yes, the Ti-89 has various integration settings that can be adjusted to improve accuracy. These can be found in the "Settings" menu under "Integration Settings". However, it is important to note that changing these settings may also affect the speed at which the calculator solves integrals.

5. Are there any limitations to using the Ti-89 for integration?

While the Ti-89 is a powerful calculator, it may not be able to solve all integrals, especially ones with very complex functions. In these cases, it is best to double-check the result or try using a different calculator or method for solving the integral.

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