How do you know when it's time for Trignometric Subsitution ?

[jkh4]

How do you know when it's time for "Trignometric Subsitution"?

How do you know when it's time for "Trignometric Subsitution"?

 

[radou]

You should be more specific about that question.

 

[ice109]

it an integration technique. it should always "work". sometimes it just makes things easier.

 

[arildno]

How do you know when it's time for "Trignometric Subsitution"?

Whenever a trigonometric substitution simplifies your integrand significantly.

 

[marcmtlca]

Usually when you see something like \frac{1}{\sqrt{1+x^2}} or \frac{1}{\sqrt{1-x^2}} or anything similar then you can think about using a trig sub. I usually think of trig sub when I see somethign that looks like the derivative of an inverse trig functions. (you should memorize those). But there are definitely many cases where a trig sub could be used...

 

[Office_Shredder]

basically whenever you see a 1 and an x², you can do some sort of trig or hyperbolic trig substitution to make things easier. Of course, if you're not sure, try solving it without the substitution, and only if you get stuck should you go for it (since if it's not useful, it can be a real pain in the ass trying to figure that out).