2-Show that the regular curve a = a(s) is a straight line if and only if its curvature k is identically equals zero .Also, show that if a = a(s) is a circle with non- zero radius a then its curvature...

Extracted text: 2-Show that the regular curve a = a(s) is a straight line if and only if its curvature k is identically equals zero .Also, show that if a = a(s) is a circle with non- zero radius a then its curvature is constant. Finally,show that a = T is identically equals zero. a(s)is a plane curve iff its torsion