How to find answer of y = 0 using double angle formulas  TOPIC_SOLVED

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How to find answer of y = 0 using double angle formulas

Postby Aaahhhh Fuuu..... on Sun Apr 17, 2011 1:39 pm

This equation cos2theta = 1, the closest equation using cos2theta double angle formula is the cos^2x - sin^2x version. But it is not exact. Can anyone show me the steps on how to complete the equation? The answer of 0 = 2y^2 is the nearest to y = 0 that I can solve without completing using dividing by two then square rooting.
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Re: How to find answer of y = 0 using double angle formulas

Postby maggiemagnet on Sun Apr 17, 2011 10:00 pm

Aaahhhh Fuuu..... wrote:This equation cos2theta = 1, the closest equation using cos2theta double angle formula is the cos^2x - sin^2x version. But it is not exact. Can anyone show me the steps on how to complete the equation? The answer of 0 = 2y^2 is the nearest to y = 0 that I can solve without completing using dividing by two then square rooting.

Why not solve the equation as it is? You have cos(2@) = 1. For what values of 2@ is the cosine equal to 1? Then divide by 2 to find the values for @.

:clap:
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Re: How to find answer of y = 0 using double angle formulas

Postby Aaahhhh Fuuu..... on Sun Apr 17, 2011 10:33 pm

"Throw yo' hands up!?"
Attach yourself to this aspect of the equation if I did not mention it: The problem is asking to convert from polar to rectangular. Looking over my question I see I did not mention this part.
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Re: How to find answer of y = 0 using double angle formulas

Postby maggiemagnet on Mon Apr 18, 2011 1:29 pm

Aaahhhh Fuuu..... wrote:"Throw yo' hands up!?"
Attach yourself to this aspect of the equation if I did not mention it: The problem is asking to convert from polar to rectangular. Looking over my question I see I did not mention this part.

I didn't know. Sorry. I didn't mean to offend you. :oops:
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Re: How to find answer of y = 0 using double angle formulas

Postby Aaahhhh Fuuu..... on Tue Apr 19, 2011 2:33 am

The only thing I need some instruction for this problem of cos2theta = 1 using polar to rectangular form. The result shown in the book is y = 0 but without any methods just the answer is useless. Thank you for your sympathies :thumb:
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Re: How to find answer of y = 0 using double angle formulas  TOPIC_SOLVED

Postby Martingale on Tue Apr 19, 2011 2:48 am

Aaahhhh Fuuu..... wrote:The only thing I need some instruction for this problem of cos2theta = 1 using polar to rectangular form. The result shown in the book is y = 0 but without any methods just the answer is useless. Thank you for your sympathies :thumb:


hmmmm...

well....we 'know' right....that



and



we also have and so

thus

and

sooooooo.....





... start replacing the above with what we know and the solution will follow...
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Re: How to find answer of y = 0 using double angle formulas

Postby Aaahhhh Fuuu..... on Tue Apr 19, 2011 3:56 pm

Thank you Martingale.
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