using de Moivre's theorem to express sin nθ and cos nθ in terms of sinθ and cosθ ExamSolutions

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[@shahzebmohammad9521]

I passed A level mathematics examinations a few years ago and I have enrolled in electrical engineering with a computer science program. if I had not found your channel a few years ago, my mindset towards mathematics would have never changed. Thank you, sir!

[@ericais2675]

Wow...I just discovered your channel today and I'm happy using it during the Corona Virus Lockdown. I've been watching your complex Numbers videos and I've gained a lot.Thanks🙏

[@stokestheorem8125]

Thank you. This is a great method to check my answer to expanding cos(5x) into cos(x). I wish I could use this theorem since expanding by the compound-angle formulas took me 1 hour.

[@alahna733]

This has been so so helpful!! Thanks so much for uploading. I just found your page yesterday and I’m understanding the maths I’m currently doing a lot easier. Subscribed and will be keeping an eye out for future vids!!🤩😎

[@ExamSolutions_Maths]

Thank you for subscribing. Best wishes.

[@megusta7972]

thanks this was so helpful , i can't begin to express how helpful this was

[@ExamSolutions_Maths]

That's okay. Thanks for watching.

[@wunnyboo463]

thank youuuuuuuu .this helped to cure my crazinesss towards math.

[@marineleroy1956]

Thank you, this was so helpful to me!

[@nadiabegum40]

Tq soo much u really help me a lot thanks once again

[@onecleanrun]

Wow. This helped me so much. Can't thank you enough.

[@ExamSolutions_Maths]

That's good.

[@ExamSolutions_Maths]

Just use the binomial expansion for (c+is)^6 and compare real parts just like I did in the video.

[@canberkpower]

Thanks a lot pal

[@ujjwalpatel6880]

Thanks sir u are great

[@TheMandhu]

thx great help

[@gilbertbett5883]

Thank you thank you thank you so much, your explanation is veeeery clear!!!!

[@ExamSolutions_Maths]

Thank you for watching

[@spacetimecontinuum4784]

this is the definite of sweet science, you explained it with no reservation

[@MrJorgie73]

using CIS notation makes it so much easier - thank you!!

[@ExamSolutions_Maths]

You're welcome

[@jermiasronaldsahureka8240]

awesome. Thank you so much

[@ExamSolutions_Maths]

+Jermias Ronald Sahureka You're welcome.

[@feradamtay527]

Thank You. That was a very good explanation of that problem.

[@ExamSolutions_Maths]

Appreciated

[@ExamSolutions_Maths]

Yes

[@user-co2nu5go9e]

ExamSolutions yes sir

[@johan_dupl]

Great explanation, thank you :D

[@ExamSolutions_Maths]

+Johan du Plessis Thank you.

[@yeswaystation27]

Great video, I've only got one question: if the question only gives us something like cos5 theta, then we can assume that z = cos5 theta + isin5 theta?

[@Amanmishra-em3vp]

its very intresting

[@nooruddinmd4437]

thnx....clearly i have got this,,,,,,,

[@ExamSolutions_Maths]

Well done

[@md.yeahiakhan3415]

thanks

[@kanyawyousif6614]

What if it was like that (Express sin4θ in terms of sinθ)?

[@96Lamo]

!!thank you so much

[@ExamSolutions_Maths]

That's okay. Thanks for using.

[@nehaiustad5205]

thank you sir..

[@ExamSolutions_Maths]

You are welcome. I am pleased to hear it helped.

[@roscoebergstedt6997]

how do you express Cos 6θ in terms of sums and differences of powers of Sinθ and Cosθ do you only use De Moivre's or also binomial?

[@nataliahuiza6554]

Muchisimas gracias, me sirvió muchisímo... pero no sé como realizar el mismo pero con seno (sen4 °)

[@hazimaznan2077]

Tq very much..

[@ExamSolutions_Maths]

You're welcome

[@loi6788]

Are we allowed to use this abbreviation during the exam?

[@bostangpalaguna228]

Do it in multiple choice section

[@srirambommidi6720]

How to calculate cos8x interms of sinx

[@bikatakasek]

makasihhh...

[@daveluz6359]

can I also do something like expressing/simplifying the sin^n to cos or sin using de moivre's theorem?
like sin^4 is equals to
3/8-1/cos2theta+1/8cos4theta
can I still get that using de moivre's theorem cuz I'm not really good at algebraic manipulation

[@ExamSolutions_Maths]

Yes. Check this out. www.examsolutions.net/tutorials/expressing-sinn%ce%b8-cosn%ce%b8-terms-sink%ce%b8-cosk%ce%b8/?level=A-Level&board=Edexcel&module=Further-Core-Maths-A-Level&topic=1898

[@jeevithagv6763]

I need expansion of sin 4(teta) in terms of cos (teta)

[@wakil7786]

Express "tan5theeta " in terms of "tan theeta". using De'movres theorm . how to solve this equation???

[@zaza8870]

Nice vid, just wondering how I’d do the reverse of this? Like finding sin^n in terms of sin(kx) etc

[@ExamSolutions_Maths]

I think this is what you are after. www.examsolutions.net/tutorials/expressing-sin-n%ce%b8-cos-n%ce%b8-terms-sin%ce%b8-cos%ce%b8/?level=A-Level&board=Edexcel&module=Further-Core-Maths-A-Level&topic=1898

[@SceneSurgeSnippets]

@@ExamSolutions_Maths That's the wrong link. This is the one he needs:
www.examsolutions.net/tutorials/expressing-sinn%ce%b8-cosn%ce%b8-terms-sink%ce%b8-cosk%ce%b8/?level=A-Level&board=Edexcel&module=Further-Core-Maths-A-Level&topic=1898

[@humayunrashid8351]

Wouldn't we need to write let c=cosx and s=sinx before doing the expansion?

[@ExamSolutions_Maths]

That's up to you. It can save space which is an advantage.

[@TheS4RP]

Nice explanation but writing imaginary part was a waste of time

[@jasonlungu5359]

Bhh he b be