(a).
If v ∈ ℒ(w), that means v = kw for some constant w. In that case:
proj(w, v) = (v·w/(w·w))w = k(w·w/(w·w))w = kw = v
Thus, ℒ(v, w) = ℒ(v, proj(w, v)) = ℒ(w).
(b).
We have:
perp(w, v) = v - proj(w, v)
So:
ℒ(v, w) = ℒ(perp(w, v) + proj(w, v), w)
Since proj(w, v) and w are collinear:
ℒ(perp(w, v) + proj(w, v), w) = ℒ(perp(w, v), w)
We don't even need v to be outside of ℒ(w), this will always work. When v ∈ ℒ(w), that will further simplify to just ℒ(w).
#Please solve this...
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So both a) and b) are true?
Yes, both seem to be true.
Thank you!
You're welcome!
By L(w) are you referring L as Span?
Yeah, I usually denote span as ℒ (script L: stands for "linear span").
Ah ok, thanks boss!
You're welcome!
@glad cliff has given 1 rep to @wicked talon
(c).
If s is a direction vector for the line, then ks for any nonzero constant k is also a direction.
But since we need a unit vector, there can only be two, just with different signs.
(d).
Two vectors have the same direction if their unit vector is the same (up to sign).
Oh okay. Ty. How would I do b)?
@glad cliff has given 1 rep to @wicked talon
How is your line, after you said In that case: true?