maths.free › Differential Geometry › Curves, arc length and curvature
Curves, arc length and curvature
Parametrised curves, the unit tangent, curvature as the turning rate.
Arc length is ∫|r′(t)| dt; curvature is how fast the unit tangent turns per unit length. A circle of radius R has curvature 1/R. Picture it: the parabola y = x² curving most tightly at its vertex. Think it: curvature and torsion determine a space curve up to rigid motion (the fundamental theorem of curves).
Nhazi ahụ ejirila · integrate sqrt(1 + 4x^2) dx from 0 to 1
Integrate sqrt(4x^2 + 1) from 0 to 1
Nzọụkwụ site n'ụdị
- \int_{0}^{1} \sqrt{4 x^{2} + 1}\, dx
First find an antiderivative F, then evaluate F(b) − F(a).
- \int \sqrt{4 x^{2} + 1}\, dx = \frac{x \sqrt{4 x^{2} + 1}}{2} + \frac{\operatorname{asinh}{\left(2 x \right)}}{4}
SqrtQuadratic rule.
- F(1) - F(0) = \left(\frac{\operatorname{asinh}{\left(2 \right)}}{4} + \frac{\sqrt{5}}{2}\right) - \left(0\right)
Fundamental theorem of calculus: plug in the limits.
- = \frac{\operatorname{asinh}{\left(2 \right)}}{4} + \frac{\sqrt{5}}{2} \approx 1.4789
Simplify.
Gosi nzaghachi
Ugbu a ị Họrọ nsogbu, mọọbụ tinye mọọbụ depụta gị. Nzọụkwụ ọbụla, inyogo, azịza ahụ echekwara ruo mgbe ịjụla.
Aịkọn ndị ahụ ejirila ebe a
Tinye ọbụla simbụl maka nkọwa zuru ezu, inyogo, na ihe ọbụla ọbụla na-egosi.
Olee otú: Curves, arc length and curvature
- First find an antiderivative F, then evaluate F(b) − F(a).
- SqrtQuadratic rule.
- Fundamental theorem of calculus: plug in the limits.
- Simplify.
Ajụjụ ndị mmadụ jụrụ
What is curvature?
For a curve, how fast its direction turns per unit length; for a surface, Gauss's combination of the two principal bendings, and Gauss's theorem says it can be measured from inside the surface without leaving it.