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core 3 help

http://www.mei.org.uk/files/papers/c305ju_dskjtr.pdf

How do you do question 2 please? Me be confused!!

Ta.
Take the sin of arcsinx.....what do you get? how can you use this for arccosx?
Really?
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fujitsum
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Original post by Rebellious-Steve
Really?


Really what?
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fujitsum
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Original post by boromir9111
Take the sin of arcsinx.....what do you get? how can you use this for arccosx?


sinx? I don't know?....
Original post by fujitsum
sinx? I don't know?....


It's just so basic really. They are the inverse of each other so they simply cancel each other out.
(edited 12 years ago)
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fujitsum
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Original post by Rebellious-Steve
It's just so basic really. They are the inverse of each other so they simply cancel each other out.


So basic why? Maybe because you know how to do it?

If its so basic, why don't you try and explain it instead of making me feel like an idiot?
Original post by fujitsum
http://www.mei.org.uk/files/papers/c305ju_dskjtr.pdf

How do you do question 2 please? Me be confused!!

Ta.


I'm on edexcel but still..... here goes:

arcsin⁡x=π6\arcsin x = \frac{\pi}{6} and you want x and arccos⁡x\arccos x in terms of π\pi

Since arcsin is the inverse of sin, take the sin of both sides

∴x=sin⁡π6=12\therefore x = \sin \frac{\pi}{6} = \frac{1}{2}.

Now you want arccos x in terms of pi, so take the inverse (arc) cos of 12\frac{1}{2} because we know x = 1/2.

∴arccos⁡x=arccos⁡12=60=π3\therefore \arccos x = \arccos \frac{1}{2} = 60 = \frac{\pi}{3} (pi radians = 180 and 60 is 180/3).

Easy? 3 marks for nothing.
(edited 12 years ago)
Original post by fujitsum
So basic why? Maybe because you know how to do it?

If its so basic, why don't you try and explain it instead of making me feel like an idiot?


Basic in the sense that it should have been one of the first things teachers had told you. I would love to help, but typing answers on my iPod is no small task.

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