- #1
Yami
- 20
- 0
Homework Statement
For two points p and q in ℝ^n, use the formula (20.3) to check that the arclength of the parametrized segment from p to q is ||p - q||.
Homework Equations
Formula (20.3):
A smooth parametrized path [tex]\gamma: [a, b]→ℝ^n[/tex]is rectifiable, and its arclength l is given by
[tex]l = \int_{a}^{b}||\gamma '||[/tex]
Norm of a point x = (x_1, ... , x_n) in ℝ^n is defined in this book as
[tex]||x|| = \sqrt{x_1^2 + ... + x_n^2}[/tex]
The Attempt at a Solution
[tex]\gamma: [q, p]→ℝ^n[/tex]
is defined as
[tex]\gamma (t) = (\gamma _1 (t), \gamma _2 (t), ... , \gamma _n (t))[/tex]
[tex]t \in [q, p][/tex]
then
[tex]\gamma '(t) = (\gamma _1 '(t), ... , \gamma _n '(t))[/tex]
[tex]||\gamma '(t)|| = \sqrt{(\gamma _1 '(t))^2+ ... + (\gamma _n '(t))^2}[/tex]
[tex]l = \int_{q}^{p} \sqrt{(\gamma _1 '(t))^2+ ... + (\gamma _n '(t))^2} dt [/tex]
I can't figure out how to integrate this though to get to ||p - q||.