Integral of trigonometric function

In summary, to find the derivative of cos2x, you can use the chain rule by taking the derivative of the outer function (cos2x) and multiplying it by the derivative of the inner function (2x), which results in -2sin2x.
  • #1
Ry122
565
2
How do I find the derivative of cos2x?
Do I use the chain rule?
u=2x
u'=2
y=cosu
y'=-sinu
dy/dx=-2sin(2x)
Edit: Sorry. I mean derivative, not integral.
 
Last edited:
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  • #2
That looks good, my friend, so I think you've got it!
 
  • #3
yes, that's correct

Now try it all in one step!
 
  • #4
what about the integral of xsin(x/2).
How would I do that?
 
  • #5
Integral or Derivative? You might want to write it out properly ...
 
  • #6
integral of xsin(x/2) dx
 
  • #7
[tex]\int x\sin{\frac x 2}dx[/tex]

Try integrating by parts.
 
  • #8
use sin(x/2) identity and try to convert everything to sin..

I have a feeling that there's an easier way to do that
 
  • #9
Ry122 said:
How do I find the derivative of cos2x?
Do I use the chain rule?
u=2x
u'=2
y=cosu
y'=-sinu
dy/dx=-2sin(2x)
Edit: Sorry. I mean derivative, not integral.

Hi Ry122! :smile:

You can also use the chain rule without having to define a u:

dcos2x/dx = (dcos2x/d(2x))(d(2x)/dx) = (-sin2x)(2). :smile:

(That way, you can eventually do these things in your head! :wink:)
 

1. What is the definition of the integral of a trigonometric function?

The integral of a trigonometric function is a mathematical concept that represents the area under the curve of a trigonometric function. It can be thought of as the reverse operation of differentiation, where the integral of a function is the function itself.

2. How do you solve the integral of a trigonometric function?

The process of solving the integral of a trigonometric function involves using integration techniques, such as u-substitution or integration by parts, to reduce the function to a simpler form that can be easily integrated. The resulting integral can then be solved using basic integration rules or by using a calculator or computer program.

3. What are the common trigonometric functions used in integrals?

The most frequently used trigonometric functions in integrals are sine, cosine, and tangent. These functions have corresponding inverse functions, arcsine, arccosine, and arctangent, which are also commonly used in integrals.

4. Can trigonometric identities be used in integrals?

Yes, trigonometric identities can be used to simplify integrals. These identities can help to transform the integral into a more manageable form, making it easier to solve. For example, the double-angle identity for cosine can be used to convert a product of cosine functions into a sum or difference, which can then be integrated more easily.

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

Integrals of trigonometric functions have many real-life applications, particularly in physics and engineering. For example, they are used to calculate the area under a velocity-time curve to determine displacement in kinematics problems. They are also used in calculating the work done by a force, as well as in calculating the area of a circular sector in geometry. Additionally, integrals of trigonometric functions are used in signal processing and in the analysis of electrical circuits.

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