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# C3 trig maths help watch

1. I will insert the question and my working out so far:

2. Ive so far got up to here:
Attachment 593692593694
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3. (Original post by Rukia12)

Ive so far got up to here:
Should be 2x inside cosine at the end.
4. (Original post by RDKGames)
Should be 2x inside cosine at the end.
how to i simplify 2cosxcos pi/3 to cos2x?
5. (Original post by Rukia12)
how to i simplify 2cosxcos pi/3 to cos2x?
Again, it should be cos(2x) and not cos(x) in that equation. Apart from that, simply evaluate 2cos(pi/3)
6. You've made a slight mistake in the final step of your working. It should read 2cos(2x)cos(pi/3). cos(pi/3) is 0.5 and you get 2 * 0.5 * cos(2x), which is simply cos(2x).
7. (Original post by RDKGames)
Again, it should be cos(2x) and not cos(x) in that equation. Apart from that, simply evaluate 2cos(pi/3)
Oh sorry I didn't understand that earlier !
8. (Original post by wajeeh1364)
You've made a slight mistake in the final step of your working. It should read 2cos(2x)cos(pi/3). cos(pi/3) is 0.5 and you get 2 * 0.5 * cos(2x), which is simply cos(2x).
Oh I see, thank you very much !

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