How to calculate this type of integral, Thanks

In summary, the first integral is not solvable and the second integral is messy but can be computed using the Wolfram Language code. The output provides a not very usable solution, but it is the best that can be obtained for an indefinite integral.
  • #1
zhaojx84
9
0
$$\int {z}^{2}\arcsin\left({\frac{a+\sqrt{392-{a}^{2}-2{z}^{2}}}{2 \sqrt{196-{z}^{2}}}}\right) dz$$
$$\int {z}^{2}\arcsin\left({\frac{a}{\sqrt{196-{z}^{2}}}}\right) dz$$
 

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  • #2
Hmm. For the first integral, I would sit down and cry. Wolfram Dev Platform doesn't do anything with it. The second integral is doable, but extremely messy. The Wolfram Langauge code
Code:
FullSimplify[Integrate[z^2 ArcSin[a/(Sqrt[196-z^2])],z] ]//TeXForm
yields
$$\frac{1}{6}\left(-a\sqrt{196-z^2}z\sqrt{\frac{a^2+z^2-196}{z^2-196}}+2744i
\left(\ln\left(\frac{3i\left(ia\sqrt{196-z^2}
\sqrt{\frac{a^2+z^2-196}{z^2-196}}+a^2-14(z+14)\right)}{686a^2
(z+14)}\right)-\ln\left(\frac{3\left(a\sqrt{196-z^2}
\sqrt{\frac{a^2+z^2-196}{z^2-196}}-ia^2-14i(z-14)\right)}{686a^2
(z-14)}\right)\right)-a\left(a^2-588\right)\tan
^{-1}\left(\frac{z}{\sqrt{196-z^2}\sqrt{\frac{a^2+z^2-196}{z^2-196}}}\right)+2
z^3\sin^{-1}\left(\frac{a}{\sqrt{196-z^2}}\right)\right).$$
I did tinker with this output just a hair (log to ln). This is not a very useable solution, but I think it's the best you're going to get for an indefinite integral.
 
  • #3
Ackbach said:
Hmm. For the first integral, I would sit down and cry. Wolfram Dev Platform doesn't do anything with it. The second integral is doable, but extremely messy. The Wolfram Langauge code
Code:
FullSimplify[Integrate[z^2 ArcSin[a/(Sqrt[196-z^2])],z] ]//TeXForm
yields
$$\frac{1}{6}\left(-a\sqrt{196-z^2}z\sqrt{\frac{a^2+z^2-196}{z^2-196}}+2744i
\left(\ln\left(\frac{3i\left(ia\sqrt{196-z^2}
\sqrt{\frac{a^2+z^2-196}{z^2-196}}+a^2-14(z+14)\right)}{686a^2
(z+14)}\right)-\ln\left(\frac{3\left(a\sqrt{196-z^2}
\sqrt{\frac{a^2+z^2-196}{z^2-196}}-ia^2-14i(z-14)\right)}{686a^2
(z-14)}\right)\right)-a\left(a^2-588\right)\tan
^{-1}\left(\frac{z}{\sqrt{196-z^2}\sqrt{\frac{a^2+z^2-196}{z^2-196}}}\right)+2
z^3\sin^{-1}\left(\frac{a}{\sqrt{196-z^2}}\right)\right).$$
I did tinker with this output just a hair (log to ln). This is not a very useable solution, but I think it's the best you're going to get for an indefinite integral.

Thank you very much. Regards.
 

FAQ: How to calculate this type of integral, Thanks

1. How do I calculate integrals with trigonometric functions?

To calculate integrals with trigonometric functions, you can use the substitution method or integration by parts. First, identify which trigonometric function is present in the integral and choose an appropriate substitution. Then, use the properties of trigonometric functions to simplify the integral and solve it. Alternatively, you can use integration by parts by selecting the trigonometric function as the first function and the remaining terms as the second function.

2. What is the difference between definite and indefinite integrals?

A definite integral has specific limits of integration, while an indefinite integral does not. This means that a definite integral will give you a specific numerical value, while an indefinite integral will give you a general expression with a constant of integration. In other words, a definite integral represents the area under a curve between two points, while an indefinite integral represents an antiderivative.

3. How do I handle improper integrals?

Improper integrals are integrals where one or both of the limits of integration are infinite or the integrand is unbounded. To calculate improper integrals, you can use the limit definition of the integral, which involves taking the limit as one or both of the limits of integration approach infinity. Alternatively, you can use a comparison test or the Cauchy principal value method to evaluate the integral.

4. Can I use a calculator to evaluate integrals?

Yes, you can use a calculator to evaluate integrals. Many calculators have built-in functions for calculating definite and indefinite integrals. However, it is important to note that calculators may not always give exact answers and may round off decimal values. It is recommended to double check your answer using other methods or by hand if possible.

5. How do I know if I have solved an integral correctly?

To check if you have solved an integral correctly, you can differentiate your answer and see if it matches the original integrand. If it does, then you have solved the integral correctly. Additionally, you can use online integral calculators or ask a classmate or teacher to verify your answer. It is also important to check for any common mistakes, such as incorrect substitution or algebra errors.

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