Integtrating secant and tangent

  • Thread starter Thread starter Aerosion
  • Start date Start date
  • Tags Tags
    Secant Tangent
Click For Summary
SUMMARY

The discussion focuses on the integration of the function sec3(2x) * tan(2x) dx. The initial approach involved separating the secant and tangent functions, leading to a substitution with u = cos(2x) and du = -sin(2x)dx. However, the correct substitution should involve u = 2x, resulting in the integral becoming (1/2) ∫ sec3(u) tan(u) du. A more efficient method suggested involves letting v = sec(u) and splitting the integrand into sec2(u) * (sec(u) tan(u)), simplifying the integration process.

PREREQUISITES
  • Understanding of integral calculus
  • Familiarity with trigonometric identities
  • Knowledge of substitution methods in integration
  • Experience with integration by parts
NEXT STEPS
  • Study integration techniques involving trigonometric functions
  • Learn about integration by substitution in depth
  • Explore the method of integration by parts
  • Practice problems involving secant and tangent functions
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques involving trigonometric functions, as well as educators looking for examples of integration methods.

Aerosion
Messages
52
Reaction score
0

Homework Statement



(integrate)sec^3(2x)*tan(2x)dx

Homework Equations





The Attempt at a Solution



Okay, so first I tried to separate secant and tangent, to get (integrate)1/cos^3(2x) * sin(2x)/cos(2x)dx. The u would be cos(2x), the du would be -du=sin(2x)dx.

I subsitute these in the aforementioned equation, whcih leaves (integrate)1/u^3 x 1/u. The problem is, I don't think this is right.
 
Physics news on Phys.org
u = 2x
du = 2 dx

\frac 12 \int \sec ^3 u \tan u du

Now let v = \sec ^2 u What is dv?
 
Aerosion said:

Homework Statement



(integrate)sec^3(2x)*tan(2x)dx

Homework Equations





The Attempt at a Solution



Okay, so first I tried to separate secant and tangent, to get (integrate)1/cos^3(2x) * sin(2x)/cos(2x)dx. The u would be cos(2x), the du would be -du=sin(2x)dx.

I subsitute these in the aforementioned equation, whcih leaves (integrate)1/u^3 x 1/u. The problem is, I don't think this is right.

There's the mistake.
 
Slight change to IMDereks post. I don't know wat dv is, can't be bothered working it out, i think my methods quicker. let v= sec u, split the integrand into sec^2 u (sec u tan u), that way the things in the brackets it dv/du, the integral is now integral: v^2 dv. simpler i think
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
19
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 22 ·
Replies
22
Views
3K
Replies
5
Views
2K
  • · Replies 105 ·
4
Replies
105
Views
7K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
9
Views
2K
  • · Replies 14 ·
Replies
14
Views
1K