Unfortunately I couldnt convert the pdf into a picture so that I could upload it but i will try to explain my problem as briefly i can

here is a pdf link btw:

<a target="_blank" title="mathhelplength (pdf)" href="http://pdfcast.org/pdf/mathhelplengt...hhelplength</a>

Right so I am faced with the following problem

"Determine the length of the lograrithmic spiral":x = e^-t * cos ty = e^-t * sin tI recal a formula

0<= t <= 2pi

l(length symbol) = $(integral from a to b) SQRT [x'(t)]^2 + [y'(t)}^ dt

I don't know how to evaluate this, could someone show me?

EDIT: New linkmathhelplength - PDFCast.org