Hello all,

Not sure what I'm missing here.  A student asked me for some help with evaluating limits involving difference quotients and trig functions.  We got through several of them, but here's one that I couldn't seem to manipulate well enough.  Am I missing an identity here?  Are conjugates helpful?  Anything factorable that I'm missing?  Hmph...

Thanks,

MM

lim(x->pi/4) of ((1 - tan(x))/(sin(x) - cos(x)))

Haha. A math teacher asking for help in a chess website. That's something cool!

PS: Yeah I can't help you sorry but at least I can joke a little bit 

Never above asking for help.

Steps:

Times top and bottom by cosx to get cosx - sinx / cosx(sinx-cosx)

Factor -1 out to get -1*lim of sinx - cosx / cosx (sinx - cosx)

Then you get -1*lim 1/cosx

Which is -1/sqrt(2) :D

You can find the solution to this problem anywhere online. Including yahoo answers lol. You teach math?

Thanks Waller.  Not thinking very well today it seems.

MM

My pleasure, everyone has a blindspot now and again.