Radians in differentiation help Watch

zanejamal
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Hello.

I'm just doing C4 june 07 paper

QP
http://eiewebvip.edexcel.org.uk/Repo...e_20070618.pdf

Mark Scheme
http://eiewebvip.edexcel.org.uk/Repo...s_20070815.pdf


I am having trouble with q8 part d.

I understand the question and how to do it and everything. I just can't understand why in the mark scheme they used radians. There is no mention of pi in the whole question. This is important as it obviously gives a completely different answer. I've probably overlooked something really simple.

Any help appreciated.
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gyrase
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You should be using radians instead of degrees in C3/C4 in general ...
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zanejamal
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(Original post by gyrase)
You should be using radians instead of degrees in C3/C4 in general ...
Not really. I only use degrees when given a range which is in terms of pi. Otherwise its usually degrees.
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gyrase
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(Original post by zanejamal)
Not really. I only use degrees when given a range which is in terms of pi. Otherwise its usually degrees.
That doesnt make sense.

I have yet to see a C4 question that involves the use of degrees over radians. Also I see the markscheme mentions arcsin(ln2), now ln2 would be a pretty damn small angle if it were in degrees.
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TheTallOne
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You can only differentiate with radians, not degrees.
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zanejamal
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(Original post by TheTallOne)
You can only differentiate with radians, not degrees.
Are you 100% sure on that ? If so thanks as that would immediately solve the problem .
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TheTallOne
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(Original post by zanejamal)
Are you 100% sure on that ? If so thanks as that would immediately solve the problem .
Absolutely certain.

You have to convert any question they ask you to differentiate with into degrees. Remember, pi radians = 180 degrees.

Edit: radians!!!
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chr15chr15
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(Original post by TheTallOne)
Absolutely certain.

You have to convert any question they ask you to differentiate with into degrees. Remember, pi radians = 180 degrees.
you just contradicted across your 2 posts and no you dont! why would it make a difference! values of theta whether in rads or degrees are both constants so it would not make the slightest difference!
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Adampolar
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(Original post by chr15chr15)
you just contradicted across your 2 posts and no you dont! why would it make a difference! values of theta whether in rads or degrees are both constants so it would not make the slightest difference!
erm no theta would be the variable. The tall one is right. You can make adjustments when using degrees but it's better just to use radians.
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Notnek
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You can differentiate using degrees but the results will be different.

e.g. the derivative of sin(x) would not be cos(x).

We always use radians in calculus because it's nicer.
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