pythagoren identities: cosec Theta = a, give other ratios

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ianhendry
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pythagoren identities: cosec Theta = a, give other ratios

Postby ianhendry » Wed Feb 01, 2012 2:23 am

I have a question that i am finding a different answer then one given. pleas explain where i am going wrong.
given: cosec Theta = a so i know sin = 1/a
asked to give remaining ratios. terminates in Quadrant 1

cos = sqrt (1-(1/a)^2)
how do they come up with sqrt (a^2-1)/a

:oops:

i left school too early 22 years ago. college algebra wasn't so bad but this is turning my mind to mush, mental block.

Hope someone can explain this for me. and ill find the reciprocals etc through that.

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stapel_eliz
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Postby stapel_eliz » Wed Feb 01, 2012 4:19 am

ianhendry wrote:cos = sqrt (1-(1/a)^2)
how do they come up with sqrt (a^2-1)/a

Simplify (1/a)2. Convert 1 - (the simplified result) to a common denominator. Take the square root. What do you get? :wink:

ianhendry
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Re: pythagoren identities: cosec Theta = a, give other ratio

Postby ianhendry » Wed Feb 01, 2012 8:14 pm

hmm i see sqrt(1-1) 1/1 *a/a the a going back under the root gets ^2 theirfore sqrt (a^2 -1)....over a+a Denominators = a... simple fraction rules. i over thought that. :thumb: :clap:

Thanks a 1000^2

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stapel_eliz
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Re: pythagoren identities: cosec Theta = a, give other ratio

Postby stapel_eliz » Wed Feb 01, 2012 11:31 pm

ianhendry wrote:hmm i see sqrt(1-1) 1/1 *a/a the a going back under the root gets ^2 theirfore sqrt (a^2 -1)

I'm sorry, but I don't understand what you mean...?

What did you get when you simplified (1/a)2?

What did you get when you subtracted the result from 1, starting with converting the 1 = 1/1 to the common denominator?

What did you get when you split the square root of a fraction into a fraction made with two square roots, and then simplified the denominator?

Please show your steps. Thank you! :wink:

ianhendry
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Re: pythagoren identities: cosec Theta = a, give other ratio

Postby ianhendry » Sat Feb 04, 2012 8:07 pm

{{{ sqrt (1-1/a^2) }}}
sqrt1-1/1-a
a/a*1/1=a/a
sqrt (a^2-1)/a

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stapel_eliz
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Postby stapel_eliz » Sun Feb 05, 2012 1:56 pm

ianhendry wrote:{{{ sqrt (1-1/a^2) }}}
sqrt1-1/1-a

How did:

. . . . .

...become:

. . . . .

:confused:

Instead, try following the steps provided earlier, starting with converting to a common denominator (in this case, would be the denominator) and then combining the two fractions. :wink:


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