i have the curve a(t) = (3t, 2t(adsbygoogle = window.adsbygoogle || []).push({}); ^{2}, 2t^{3}) and that a'(t) = (3, 4t, 6t^{2}). my textbook tells me to verify that the tangent lines make a constant angle with the line y = 0, z = x so basically the vector (1, 0, 1).

using the definition of the dot product [itex] a * b = |a| |b| cos(\theta) [/itex] i have [itex] cos(\theta) = \frac{3 + 6t^2}{\sqrt{2}\sqrt{9 + 16t^2 + 36t^4}} [/itex]

however it doesn't look to me that this is will give a constant angle. the parameter t doesn't seem to cancel out so it wouldn't be constant in this case. have i missed something?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Checking that a parametric curve is general helix

**Physics Forums | Science Articles, Homework Help, Discussion**