Friday

July 25, 2014

July 25, 2014

Posted by **Shayna** on Wednesday, January 18, 2012 at 8:45pm.

- Calculus -
**Steve**, Thursday, January 19, 2012 at 4:48amLet x = secθ

dx = secθtanθ dθ

θ = arcsec x

Int(arcsec(x) dx)

= Int(θ secθtanθ dθ)

now integrate by parts

u = θ

du = dθ

dv = secθtanθ dθ

v = secθ

Int(θ secθtanθ) = θsecθ - Int(secθ dθ)

To integrate secθ you have to resort to a trick:

secθ (secθ + tanθ)/(secθ + tanθ) dθ

now the top is sec^2θ + secθtanθ

let u = secθ + tanθ and we have

1/u du

so, Int(secθ dθ) is ln|secθ + tanθ|

and we end up with

Int(θ secθtanθ) = θsecθ - ln|secInt(θ secθtanθ) = θsecθ - Int(secθ dθ) + tanInt(θ secθtanθ)

= θsecθ - Int(secθ dθ)|

Now, what does all that equal in x's?

θ = arcsec(x)

secθ = x

tanθ = √(x^2-1)

and you have your answer.

- Calculus - PS -
**Steve**, Thursday, January 19, 2012 at 4:52amcopy-paste error. That last complicated line should read:

Int(θ secθtanθ) = θsecθ - Int(secθ dθ)

= θsecθ - ln|secθ + tanθ|

**Related Questions**

Calculus - Find the volume of the solid whose base is the region in the xy-plane...

Calculus - Find the exact coordinates of the centroid. y = sqrt[x], y = 0, x = 9...

Calculus - Graph the curve and find its exact length. x = e^t + e^-t, y = 5 - 2t...

Calculus Help Please Urgent!!! - Prove that the integral on the interval [a,b] ...

CALCULUS 2!!! PLEASE HELP!! - I'm having trouble with this question on arc ...

Calculus - Evaluate the indefinite integral: 8x-x^2. I got this but I the ...

Calculus - Given the equation xy = 2, set up an integral to find the length of ...

Calculus II - Evaluate using u-substitution: Integral of: 4x(tan(x^2))dx ...

Is this how you derive the formula for arc length? - For a smal change in x, dx...

Calculus URGENT test tonight - Integral of: __1__ (sqrt(x)+1)^2 dx The answer is...