Integration By Substitution Problem (Trig)

In summary, the integral can be solved using substitution techniques, with the use of two substitutions for the cot and csc functions. It may be helpful to convert these functions into their sine and cosine equivalents.
  • #1
KingKai
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Homework Statement



Integrate the following using substitution techniques

∫e3tcsc(e3t)cot(e3t) dt

Homework Equations



csc(t) = 1/sin(t)

cot(t) = 1/tan(t)

cot(t) = cos(t)/sin(t)

1 + cot2(t) = csc2(t)

The Attempt at a Solution



∫e3tcsc(e3t)cot(e3t) dt

set u = cot(e3t)

du = (3e3t)(- csc2(e3t)) dt


Make Substitution,


∫e3tcsc(e3t) (u) (1/(3e3t)(- csc2(e3t)) du



Whoops, csc does not cancel out..



My friend told me I had to make TWO substitutions, following this advice my head proceeded to explode.

After recollecting the pieces of my skull fragments and carefully gluing them together again, I posted this question.
 
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  • #2
KingKai said:

Homework Statement



Integrate the following using substitution techniques

∫e3tcsc(e3t)cot(e3t) dt

Homework Equations



csc(t) = 1/sin(t)

cot(t) = 1/tan(t)

cot(t) = cos(t)/sin(t)

1 + cot2(t) = csc2(t)

The Attempt at a Solution



∫e3tcsc(e3t)cot(e3t) dt

set u = cot(e3t)

du = (3e3t)(- csc2(e3t)) dt


Make Substitution,


∫e3tcsc(e3t) (u) (1/(3e3t)(- csc2(e3t)) du



Whoops, csc does not cancel out..



My friend told me I had to make TWO substitutions, following this advice my head proceeded to explode.

After recollecting the pieces of my skull fragments and carefully gluing them together again, I posted this question.

I would be inclined to turn the cot and csc functions into their sine and cosine equivalents, and go from there.
 

Related to Integration By Substitution Problem (Trig)

1. What is integration by substitution in trigonometry?

Integration by substitution is a method used to solve integrals involving trigonometric functions. It involves substituting a variable with a trigonometric function in order to simplify the integral and make it easier to solve.

2. How do you find the substitution for integration by trigonometric functions?

The substitution for integration by trigonometric functions depends on the specific integral being solved. However, a general rule is to look for a function and its derivative in the integral that can be replaced by a trigonometric function and its derivative. For example, if the integral contains √(1-x²), the substitution x = sinθ can be used.

3. What are the steps for solving an integral by substitution in trigonometry?

The steps for solving an integral by substitution in trigonometry are as follows:
1. Identify the function and its derivative in the integral.
2. Choose an appropriate substitution, usually involving a trigonometric function.
3. Replace the function and its derivative in the integral with the chosen substitution.
4. Simplify the integral using trigonometric identities and algebraic manipulation.
5. Integrate the simplified integral.
6. Substitute back the original variable to get the final answer.

4. What are some common trigonometric substitutions used in integration?

Some common trigonometric substitutions used in integration include:
1. x = sinθ
2. x = cosθ
3. x = tanθ
4. x = cotθ
5. x = secθ
6. x = cscθ
Note that these substitutions can also be used with their respective inverse functions.

5. Can integration by substitution be used for all trigonometric integrals?

No, integration by substitution may not work for all trigonometric integrals. Some integrals may require other methods such as integration by parts or the use of trigonometric identities. It is important to practice and develop a good understanding of different integration techniques in order to determine the best method for solving a specific integral.

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