Definite trigonometric integral

In summary, the conversation is about finding the integral of x^6*arcsin(x) from 0 to 1. The person tried substituting arcsin(x) with y, but abandoned it due to complications. They then tried using definite integral properties, but did not make progress. They solved it using integration by parts, but were looking for a shorter method. The other person suggested trying multiple integrations by parts, but the first person had already solved it using a single integration by parts. The first person was wondering if there was an even shorter method, and the second person asked for their work to see if it was the shortest possible way. The first person then explained their method using a standard substitution and simplification. The
  • #1
Krushnaraj Pandya
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Homework Statement


solve ##\int_0^1 x^6 \arcsin{x} dx##
 
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  • #2
Krushnaraj Pandya said:

Homework Statement


solve ##\int_0^1 x^6 \arcsin{x} dx##

3. The Attempt at a Solution

I tried substituting arcsinx=y, but abandoned it a few steps later ahead as it started taking a more complicated form. I have a feeling definite integral properties play a larger role here and tried applying some but didn't get anywhere. I'd appreciate some help, thanks
PS- I solved it using Integration by parts. Looking for a shorter method if exists
 
  • #3
Try integrating by parts several times. That is a little tedious but will get you the final answer.
Edit: wrote the above before your PS came up. I think by parts will be the shortest way.
 
  • #4
nomadreid said:
Try integrating by parts several times. That is a little tedious but will get you the final answer.
I solved it by a single integration by parts...I'm looking for an even shorter method
 
  • #5
did you get (35π -32)/490 ?
 
  • #6
Krushnaraj Pandya said:
I solved it by a single integration by parts...I'm looking for an even shorter method

Show your work. Maybe what you did is the shortest possible way, but we cannot tell if you don't show us.
 
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  • #7
nomadreid said:
did you get (35π -32)/490 ?
Yes I did. (I took sin inverse as first function and x^6 as second, after 2 or 3 substitutions I got this answer)
 
  • #8
Ray Vickson said:
Show your work. Maybe what you did is the shortest possible way, but we cannot tell if you don't show us.
I simply took arcsinx as first function, and x^6 as second function. It was just a simple by-parts and the second term (derivative of arcsin*integral of x^6) was an algebraic term- I just used 2 substitutions to evaluate that and get the second term as well. What I mean by a shorter method is whether I can avoid the entire by-parts procedure and just use definite-integral properties to calculate this (i.e by a different approach)
 
  • #9
Sounds good. Which substitutions?
PS (after your edit): the parts method is pretty straightforward. If you want to play around a bit, you can also express arcsin x as -i*ln(i*x + (1-x2)½), but that would be longer to work with, and you would still end up using parts.
 
  • #10
nomadreid said:
Sounds good. Which substitutions?
PS (after your edit): the parts method is pretty straightforward. If you want to play around a bit, you can also express arcsin x as -i*ln(i*x + (1-x2)½), but that would be longer to work with, and you would still end up using parts.
haha, I guess a direct by parts is the shortest method possible. keeping arcsin as arcsin seems a better option, as for the substitutions I used- Its totally lost somewhere in my ton of rough work (side effects of a calculus course) but I remember It was something pretty standard like setting the term in the square-root in the denominator as t^2 and then further simplification
 
  • #11
Krushnaraj Pandya said:
haha, I guess a direct by parts is the shortest method possible. keeping arcsin as arcsin seems a better option, as for the substitutions I used- Its totally lost somewhere in my ton of rough work (side effects of a calculus course) but I remember It was something pretty standard like setting the term in the square-root in the denominator as t^2 and then further simplification
this is probably what the question-maker had in mind I guess, I see no other way to shorten or quicken this
 

FAQ: Definite trigonometric integral

1. What is a definite trigonometric integral?

A definite trigonometric integral is a type of integral in calculus that involves trigonometric functions, such as sine, cosine, and tangent. It is used to find the area under a curve or the value of a function at a specific interval.

2. How do you solve a definite trigonometric integral?

To solve a definite trigonometric integral, you can use various integration techniques, such as substitution, integration by parts, or trigonometric identities. It is important to first identify the type of integral and then choose the appropriate method for solving it.

3. What are the common trigonometric identities used in definite trigonometric integrals?

Some of the common trigonometric identities used in definite trigonometric integrals include the Pythagorean identities, double angle identities, and half angle identities. These identities help to simplify the integral and make it easier to solve.

4. Can definite trigonometric integrals be solved using a calculator?

Yes, definite trigonometric integrals can be solved using a calculator, but it is important to make sure the calculator is set to the correct mode (degrees or radians) and to double-check the answer for accuracy.

5. What are some real-life applications of definite trigonometric integrals?

Definite trigonometric integrals have many real-life applications, such as in physics, engineering, and astronomy. They are used to calculate the displacement, velocity, and acceleration of moving objects, and to analyze the behavior of waves and periodic phenomena.

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