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Looking at the answer of this question:

Show that the arc length of a curve is invariant under rigid transformation.

I don't understand why if $T$ is linear then

$$(T\circ \gamma)'(t)=T\circ \gamma'(t)$$

I will appreciate any comment to help me to understand

user326159
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1 Answers1

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This is an application of the chain rule together with the fact that for any linear transformation $T,\ T'(x)=T:$

$(T\circ \gamma)'(t)=T'(\gamma (t))(\gamma'(t))=T(\gamma '(t))=T\circ \gamma'(t).$

Matematleta
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