How do you find the length of the line x=At+B, y=Ct+D, a<=t<=bx=At+B,y=Ct+D,atb?

1 Answer
Mar 4, 2018

l = abs(a-b)sqrt(A^2+C^2)l=|ab|A2+C2

Explanation:

Given the line

L -> p = p_0 + vec v tLp=p0+vt

with

p = (x,y)p=(x,y)
p_0 =(B,D)p0=(B,D)
vec v = (A,C)v=(A,C)

we have

p_a = p_0 + vec v apa=p0+va
p_b = p_0 + vec v bpb=p0+vb

and then

l = norm(p_a-p_b)= norm(p_0+ (vec v) a - p_0 - (vec v) b) = norm(vec v(a-b)) = abs(a-b)norm (vec v) = abs(a-b)sqrt(A^2+C^2)l=papb=p0+(v)ap0(v)b=v(ab)=|ab|v=|ab|A2+C2