Math Help - Curvature

I have to find the curvature of the curve with the equation (4sint)i+(4sint)j+(4cost)k. I use the magnitude of r'xr'' over the magnitude of r'^3. Nothing cancels out for me. Can anybody help??

Originally Posted by Mathwizz

I have to find the curvature of the curve with the equation (4sint)i+(4sint)j+(4cost)k. I use the magnitude of r'xr'' over the magnitude of r'^3. Nothing cancels out for me. Can anybody help??

If "Nothing cancels out", then how can anyone help?

What did you get for

I get