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This has been bugging me for a bit. I think I'm probably missing something pretty easy.

AdotB= ABcos(θ), where θ is the angle betweenAandB.

There is the little shortcut that says whereBis the derivative ofA,AdotB= AB. Clearly then cos(θ) = 1, and the angle between a vector and its derivative is 2nPi, where n=0, 1, 2... Intuitively this would not be true, and is clearly not true for an orbit (which is what I use it for). There the angle betweenRandVwhereVis the derivative ofRis 90°+the flight path angle.

What am I missing? How are both these things true?

Note: I don't want to mathematical derivation of the shortcut. I have that. I want to understand it in reality.

I hope this is in the correct forum

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# Dot Product of a Vector and its Derivative- Reality

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