17-20 (a) Find the unit tangent and unit normal vectors T(t) and N(t). (b) Use Formula 9 to find the curvature. 17. r(t) (2 sin t, 5t, 2 cos t) 18. r(t) = (t°, sin t – t cos t, cos t + t sin t), t>0...

I would need some help with problem #18, please?

(a) Find the unit tangent and unit normal vectors T(t) and N(t) .
(b) Use Formula 9 to find the curvature.

Extracted text: 17-20 (a) Find the unit tangent and unit normal vectors T(t) and N(t). (b) Use Formula 9 to find the curvature. 17. r(t) (2 sin t, 5t, 2 cos t) 18. r(t) = (t°, sin t – t cos t, cos t + t sin t), t>0 19. r(1) = (/2t, e', e-) 20. r(t) = (1, r', 1²)