http://i.imgur.com/giyhyA8.png

Can someone tell me how that circled angle is determined to be delta theta/2? Some background, a rope is draped over a pulley and is pulled on one end a short distance.

Question

http://i.imgur.com/giyhyA8.png

Can someone tell me how that circled angle is determined to be delta theta/2? Some background, a rope is draped over a pulley and is pulled on one end a short distance.

anonymous · Answer

I believe it represents a change in theta/2, or 1/2 way point of the change of angle theta

anonymous · Answer

actually it just looks like 1/2 the angle theta

henryblah · Answer

The circled angle is correct, but I don't know how they got it from the rest of the diagram.

anonymous · Answer

I'll probably steer you wrong

henryblah · Answer

This might help the background. http://i.imgur.com/3qICD8S.png

ganeshie8 · Answer

you familiar wid 'alternate interior angles' theorem ?

henryblah · Answer

I've learnt it a year ago I think let me see if I can apply it

ganeshie8 · Answer

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ganeshie8 · Answer

when lines are parallel,
alternate interior angles are congruent.

we can use this to derive the redcircled angle

henryblah · Answer

I don't see the parallel lines sorry :(

anonymous · Answer

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