# Finding an integral

1. Apr 5, 2008

### ns5032

1. The problem statement, all variables and given/known data

I would just like some help on how to find the integral of:
sin(x) / cos(x)^2

2. Relevant equations

integration by parts?
uv-integral of v(du)

3. The attempt at a solution
I tried using integration of parts with u = cos(x)^2 and dv = sin(x) but I just got myself in a bigger mess.

I noticed that sin(x) / cos(x)^2 was equal to tan(x)sec(x). Not sure if that helps though...

Help please?!

2. Apr 5, 2008

### NanakiXIII

I'd go for a substitution.

3. Apr 5, 2008

### R.Harmon

Try the substitution cos(x)^2.

4. Apr 5, 2008

### rootX

what's integral of [(-2*u)/(1-u^2)]/-2

or

try to see 1/x connection

Last edited: Apr 5, 2008
5. Apr 5, 2008

### rock.freak667

$$\int \frac{sinx}{cos^2x} dx$$

$$\equiv \int \frac{sinx}{cosx} \times \frac{1}{cosx}dx$$

What is another way to write $\frac{sinx}{cosx}$?
and similarly $\frac{1}{cosx}$?

Should be pretty standard after you see it.

6. Apr 6, 2008

### ns5032

Got it. Thank you everyone.

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