Recent content by multivariable

i got that the actual K should be 1/ (r^2 + 1)^(1/2) which i can't seem to relate to the K given.. when i subsitute it, it's too messy

yea, i dnt know exactly what I'm doing when I am plugging things in.. like f(theta) is a vector?.. f(theta) = r cos theta + r sin theta... or... I just don't understand :( but i get the math, just not what I am subsituting..

Homework Statement A Curve C is given by the polar equation r=f(theta). Show that the curvature K at the point (r, theta) is K=|2(r')^2 - rr'' + r^2| -------------------- [(r')^2 + r^2]^(3/2) *Represent the curve by r(theta) = r<cos theta, sin theta> Homework Equations I...

wow.. I had copied the property [R(t) x R'(t)]' = blah blah blah.. incorrectly from my book... It makes perfect sense now, thank you for the help!

[SIZE="3"]I can't seem to figure out how to prove the property for R(t) = <f(t), g(t), h(t)> : D[SIZE="1"]t[SIZE="3"][R(t) X R'(t)] = R(t) X R"(t) Any suggestions?!