# math

posted by
**mathstudent**
.

How do I derive the secant reduction rule?

Integral (sec x)^n dx

= Integral (sec x)^(n-2) * (sec x)^2 dx

= Integral ((tan x)^2 + 1)^(n/2-1) * (sec x)^2 dx

Doing a substitution with:

u = tax x

du = (sec x)^2 dx

= Integral (u^2 + 1)^(n/2-1) * du

At this point I'm stuck. Any ideas? Thanks!