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Further Pure 2 June 12

Hi Guys,

having a bit of a (non-light bulb) moment with Q8 part c? Anyone help me out?

(Exam board AQA)

Many thanks
(edited 9 years ago)
Original post by Hunkybm
Hi Guys,

having a bit of a (non-light bulb) moment with Q8 part c? Anyone help me out?

Many thanks


Which exam board?
Reply 2
Completely forgot, sorry! AQA
Original post by Hunkybm
Completely forgot, sorry! AQA


No worries. :smile:

Well, hopefully from part (b) you would have got that cos4θ=18cos8θ+12cos4θ+38\cos^4 \theta = \dfrac{1}{8} \cos 8\theta + \dfrac{1}{2} \cos 4\theta + \dfrac{3}{8}

For part c, write the cos^4(theta) on the LHS as above and it should be easy to solve then. :smile:
(edited 9 years ago)
Reply 4
Yes, thank you!!
Turns out, having had a second look, I'd written the right hand side equal to cosX + 5 instead of cos8X!!

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