Marcop

Asking this question labels you a m***n. So, for you, the answer is never. 

testing edit ability.

Thanks guests

I don't remember where it came from. I asked it once before, a very long time ago. I got no responses.

I saw it in my watchlist and I just thought I'd ask again. :)

Ok I'll try

Thanks Tiggsy :/

Thanks everyone, you all helped :)

Tiggsy, I can follow what you have done and I can see that early on I/you had already determined that 

d/dx secx = tanx secx

I suppose that the bit that is still troubling me is multiplying by (secx+tanx)/(secx+tanx)

I mean I can see that it works but I would not think of it ... is there something I am missing, I mean a hint of what to do or something?  Is this just a 'trick' that I must commit to memory for questions such as this?  

Is there some extra working that can be thrown in to make it more obvious?       

Thanks very much.  :)

Are you the same guest or 3 different guests?

Anyway I'll take a proper look in the morning. 

I don't know the reduction formula but maybe I can follow the rest://

Thanks but I don't want the answer I want a full understandable explanation. 

Thanks Melody and anonymous 

Thank you Alan. 

Thanks - Now I get it!  

GEE, that's brilliant.

Thanks Melody and CPhill!!

The answers are the same but they look different.  It will take me a while to work it all out!