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C3 trig

I have to put the equation in the photo in terms of one trigonometric function. What is wrong with what I did? The answer is meant to be 1/4sin^2(2x) ImageUploadedByStudent Room1446660607.234766.jpg


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Reply 1
Avatar for ubisoft
ubisoft
3
What you done there is correct. Show what the actual question was.
Reply 2
Avatar for JD1lla
JD1lla
3
Rotate that picture, or use latex (google latex tsr and it should come up to the thread, I can't remember where it is located)

I'm struggling to understand what you want too
Original post by ubisoft
What you done there is correct. Show what the actual question was.


It's 3f ImageUploadedByStudent Room1446660949.949507.jpg


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Original post by JD1lla
Rotate that picture, or use latex (google latex tsr and it should come up to the thread, I can't remember where it is located)

I'm struggling to understand what you want too


I am using no the double angle formula: sin2A = 2sinAcosA


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Reply 5
Avatar for TeeEm
TeeEm
19
Original post by anoymous1111
I have to put the equation in the photo in terms of one trigonometric function. What is wrong with what I did? The answer is meant to be 1/4sin^2(2x) ImageUploadedByStudent Room1446660607.234766.jpg


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I get the same answer like you in 2 different ways
Original post by JD1lla
Rotate that picture, or use latex (google latex tsr and it should come up to the thread, I can't remember where it is located)

I'm struggling to understand what you want too


ImageUploadedByStudent Room1446661082.407596.jpg


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Original post by TeeEm
I get the same answer like you in 2 different ways


Apparently it is wrong.... I don't know why


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Reply 8
Avatar for ubisoft
ubisoft
3
Original post by anoymous1111


Why did you just square root it out of nowhere? that changes the expression.

Think of double angle expressions that you can use.
Reply 9
Avatar for JD1lla
JD1lla
3
Original post by anoymous1111
Apparently it is wrong.... I don't know why


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Post your methodology, I don't know how you're using that identity (well I can guess). I don't know how the posters above have also got the same answer as you. Are you all mis-reading the question/OPs post?

She wrote cos^2, not cos2
Original post by JD1lla
Post your methodology, I don't know how you're using that identity (well I can guess). I don't know how the posters above have also got the same answer as you. Are you all mis-reading the question/OPs post?

She wrote cos^2, not cos2


There isn't really any methodology....like obviously 1/2(2) =1 so I'm just rewriting the equation so that I can use the formula to simplify part of it....


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Reply 11
Avatar for TeeEm
TeeEm
19
Original post by anoymous1111
Apparently it is wrong.... I don't know why


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it is wrong because now that you posted the question there is no square root anywhere in the question....
Original post by anoymous1111
There isn't really any methodology....like obviously 1/2(2) =1 so I'm just rewriting the equation so that I can use the formula to simplify part of it....


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But you can't square root something that isn't part of an equation
You can rewrite it as
(sinthetacostheta)^2 and then proceed with the method you did and expand at the end.
Reply 13
Avatar for ubisoft
ubisoft
3
Original post by anoymous1111
There isn't really any methodology....like obviously 1/2(2) =1 so I'm just rewriting the equation so that I can use the formula to simplify part of it....


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Square rooting the whole thing is not rewriting it; it changes the expression. It's not an equation.
Original post by TeeEm
it is wrong because now that you posted the question there is no square root anywhere in the question....


Ooooooooooops :frown: sorry everyone I'm so stupid.....I thought I had included the question. Why can't I square root the whole thing? Is it because it's not stated that it is equal to 0 therefore I can only rearrange it


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Reply 15
Avatar for JD1lla
JD1lla
3
sin2x−sin4xsin^{2}x-sin^{4}x is what I got, which is another form of the answer you seek, but I assume I used different methodology to the way you require. I suppose this doesn't help :P
(edited 8 years ago)
Original post by anoymous1111
Ooooooooooops :frown: sorry everyone I'm so stupid.....I thought I had included the question. Why can't I square root the whole thing? Is it because it's not stated that it is equal to 0 therefore I can only rearrange it


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If you have the value 9.
9 is identical to 3^2 but it isn't identical to sqrt(9)
Just like
cos^2sin^2 is identical to (costhetasintheta)^2 but not identical to sqrt(cos^2thetasin^2theta)
Reply 17
Avatar for kkboyk
kkboyk
21
Original post by anoymous1111
I have to put the equation in the photo in terms of one trigonometric function. What is wrong with what I did? The answer is meant to be 1/4sin^2(2x) ImageUploadedByStudent Room1446660607.234766.jpg


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Factorise it first into (sinxcosx)^2, and then do what you did for inside the bracket and then expand it (except you do not square root it).
Original post by Windowswind123
If you have the value 9.
9 is identical to 3^2 but it isn't identical to sqrt(9)
Just like
cos^2sin^2 is identical to (costhetasintheta)^2 but not identical to sqrt(cos^2thetasin^2theta)


Haha I know I don't know what I was thinking! Sorry I wasted your time!


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Original post by JD1lla
sin2x−sin4xsin^{2}x-sin^{4}x is what I got, which is another form of the answer you seek, but I assume I used different methodology to the way you require. I suppose this doesn't help :P


That's great thank you


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