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Q: Find curvature and torsion of helix r(t) = (cos t, sin t, t). Unit speed? |r'| = √2: reparametrize or use formula. κ = |r'×r''|/|r'|³. r'' = (-cos t,-sin t,0). r'×r'' = (sin t,-cos t,1)... compute: |r'×r''| = √2. κ = √2/(√2)³ = 1/2! τ = det[r',r'',r''']/|r'×r''|²: r''' = (sin t,-cos t,0): det = 1: τ = 1/2! (Helix: κ = τ = 1/2!)