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April 27, 2024, 09:31:04 pm
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Author Topic: Holiday homeworkk  (Read 8640 times)  Share 

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mandy

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Holiday homeworkk
« on: December 01, 2009, 12:25:08 pm »
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Can you help me prove the following identity:

=

Been trying for a while and nothing good's happening :(
Thank youu.
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Damo17

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Re: Holiday homeworkk
« Reply #1 on: December 01, 2009, 01:06:44 pm »
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Quote from: mandy on December 01, 2009, 12:25:08 pm
Can you help me prove the following identity:

=

Been trying for a while and nothing good's happening :(
Thank youu.

LHS:

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mandy

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Re: Holiday homeworkk
« Reply #2 on: December 01, 2009, 01:29:05 pm »
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Thanks a lot :]
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mandy

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Re: Holiday homeworkk
« Reply #3 on: December 01, 2009, 02:07:53 pm »
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I have another qn:

X = tan2x


Do I just multiply across like normal fractions :S
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Cataclysmic

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Re: Holiday homeworkk
« Reply #4 on: December 01, 2009, 02:17:04 pm »
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Is it just me or is [tex] stuff not working?
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mandy

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Re: Holiday homeworkk
« Reply #5 on: December 01, 2009, 02:18:31 pm »
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yeah, it wasn't working for me either.
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Cataclysmic

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Re: Holiday homeworkk
« Reply #6 on: December 01, 2009, 02:25:02 pm »
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Yeah just multiply the left side out, use sin^2(x) + cos^2(x) = 1 and you'll end up with sin^2(x)/cos^2(x) on the left side.
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mandy

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Re: Holiday homeworkk
« Reply #7 on: December 01, 2009, 02:27:26 pm »
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okaaay, got it :O
thank you !
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mandy

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Re: Holiday homeworkk
« Reply #8 on: December 01, 2009, 03:10:42 pm »
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(1 + cos x)(1 - cos x) =


I expanded the LHS, and got
1 - cos2x, which equals sin2x, right?
Then how does that equal the RHS?
Am I even doing this right :(
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Damo17

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Re: Holiday homeworkk
« Reply #9 on: December 01, 2009, 03:30:50 pm »
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Quote from: mandy on December 01, 2009, 03:10:42 pm
(1 + cos x)(1 - cos x) =


I expanded the LHS, and got
1 - cos2x, which equals sin2x, right?
Then how does that equal the RHS?
Am I even doing this right :(

you are correct.



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mandy

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Re: Holiday homeworkk
« Reply #10 on: December 01, 2009, 03:38:19 pm »
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wow, i never knew that worked, thank you.
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mandy

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Re: Holiday homeworkk
« Reply #11 on: December 01, 2009, 09:10:30 pm »
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another one:

sec x - tan x =

This is what I did:
LHS = -
     
      =

Is that the same as the RHS?

 
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kamil9876

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Re: Holiday homeworkk
« Reply #12 on: December 01, 2009, 09:16:56 pm »
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Voltaire: "There is an astonishing imagination even in the science of mathematics ... We repeat, there is far more imagination in the head of Archimedes than in that of Homer."

mandy

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Re: Holiday homeworkk
« Reply #13 on: December 01, 2009, 09:30:15 pm »
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Quote from: kamil9876 on December 01, 2009, 09:16:56 pm


For that first bit, why is it multiplying? And where did you get 1 -sinx and 1 + sinx from :S
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zzdfa

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Re: Holiday homeworkk
« Reply #14 on: December 01, 2009, 09:41:38 pm »
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He multiplied top and bottom by the 'conjugate', just like you would to find 1/(1-3i)

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