Posted by Soroban on October 03, 2002 at 17:42:02:
In Reply to: Diff EQ posted by Amanda on October 03, 2002 at 12:26:09:
: I am trying to work a problem involving verifying that a given (y) is an explicit solution to a differential equation. This involves trigonometric functions and I am having trouble seeing things that cancel to zero. It be greatly appreciated if someone could reduce the following to omit the natural log and put the equation involving sin x and cos x only.
: ln (sec x + tan x)
: The problems I am having are mainly in the natural log; is there any way to get that out of the way??
No, there isn't.
Why are you "having problems" with natural logs?
You can't remember that the derivative of ln(x) is 1/x ?
The good news: the derivative of ln|sec x + tan x| is sec x.