Could someone please explain why PQ in the diagram below is rΔθ? Isn't rΔθ arc length?(adsbygoogle = window.adsbygoogle || []).push({});

The best reason I can think of is that it's only an approximation for when the angle is very small, so PQ≈arclength=rΔθ. Not 100% sure though.

The diagram is from the first volume of the Feynman lectures in 18-3, in the section where he talks about rotation of rigid bodies.

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# Is this arc length?

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