View Full Version : How to find the antiderivative of trig
Vi Nguyen
May 1, 2009, 09:11 PM
Can anyone help me in finding the antiderivative of:
sec²(x)e^(tan(x))
Antidifferentiation is so confusing!!
galactus
May 2, 2009, 05:26 AM
\int sec^{2}(x)e^{tan(x)}dx
Actually, this one is not that bad if you see the sub to make.
Let u=tan(x), \;\ du=sec^{2}(x)dx
Make the subs and it's easy.
Vi Nguyen
May 2, 2009, 10:42 AM
Does this mean this mean that I find the integral of e^(tan(X)), then is the answer e^(tan(x))/tan(x) +C ?
\int sec^{2}(x)e^{tan(x)}dx
Actually, this one is not that bad if you see the sub to make.
Let u=tan(x), \;\ du=sec^{2}(x)dx
Make the subs and it's easy.
galactus
May 2, 2009, 10:49 AM
No, just make the substitution. Have you learned u substitution?
If we let u=tan(x), \;\ du=sec^{2}(x)dx, it whittles down to
\int e^{\overbrace{u}^{\text{tan(x)}}}\underbrace{du}_{ \text{sec^2(x)dx}}
See why? The sec^{2}(x)dx is taken care of by the du and the tan(x) is u as
the power in e.
Now, integrate and resub. e^{u} is the easiest to integrate because it stays the same.
Anti-differentiation is not that confusing.Just think of it as the opposite of differentiation.
Once you find the anti-derivative, differentiate and you should get back to the original, e^{tan(x)}sec^{2}(x)
Vi Nguyen
May 2, 2009, 07:00 PM
Thanks you're a legend! ;p
No, just make the substitution. Have you learned u substitution?.
If we let u=tan(x), \;\ du=sec^{2}(x)dx, it whittles down to
\int e^{\overbrace{u}^{\text{tan(x)}}}\underbrace{du}_{ \text{sec^2(x)dx}}
See why?. The sec^{2}(x)dx is taken care of by the du and the tan(x) is u as
the power in e.
Now, integrate and resub. e^{u} is the easiest to integrate because it stays the same.
Anti-differentiation is not that confusing.Just think of it as the opposite of differentiation.
Once you find the anti-derivative, differentiate and you should get back to the original, e^{tan(x)}sec^{2}(x)