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AonZ
 3 years ago
Eliminate A from each pair of parametric equations
x = 3sinA
y= 6sin2A
AonZ
 3 years ago
Eliminate A from each pair of parametric equations x = 3sinA y= 6sin2A

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dan815
 3 years ago
Best ResponseYou've already chosen the best response.0is it like that or is it sin^2A

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0from x= 3sin(a), what would sin(a) be?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0.. right... ... is x= 3sin(a), what you have or x = 3cos(a)?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Btw, what do you mean by eliminate? Are you to convert this in to a rectangular equation with y in terms of x or are you to have both x and y written in terms of something else that isn't A? @AonZ

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0write the equation simply without A

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0@genius12 pretty much, is just conversion to rectangular

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0So y in terms of x and not A right?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0\[\bf x=3\sin(A) \implies \frac{x}{3}=\sin(A) \implies \sin^{1} \left( \frac{x}{3}\right)=A\]Plug this value of A in y = 6sin(2A) and you're done. @AonZ

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1369437887196:dw

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0well he shudnt get the asnwer too easily so its all good :)

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Both @dan815 and mine rectangular forms work. Except his makes it more obvious that cosine and sine can be used parametrically to give an ellipse as dan's rectangular form is the equation of an ellipse.

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1369437893899:dw i dont it get when u went into that part

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Rearrange x and y so that:\[\bf \frac{y}{4x}=\cos(A) \ and \ \frac{x}{3}=\sin(A)\]Squaring both sides of both equations gives:\[\bf \left( \frac{y}{4x} \right)^2=\cos^2(A) \ and \ \left( \frac{x}{3} \right)^2=\sin^2(A)\]Adding both equations and using the identity cos^2(A) + sin^2(A) = 1 gives u the rectangular form. @AonZ

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0I just realised, @dan815 rectangular form actually won't be an ellipse even thought i looks like it will be lol. There is an x in the denominator under y which means it can't be the equation of an ellipse.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0not sure you can get rid of the "x" though, I got the same :S

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0u dont need to they just want an equation without A

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0thank you so much :D understood @genius12 way much better

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=%28y%2F%284x%29%29%5E2%2B%28x%2F3%29%5E2%3D1

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0was hard to read dan's writting :P

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0if u wanna see a nice graph :)

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0can i pls get help on 1 more question? http://openstudy.com/study#/updates/519ff981e4b04449b221f091

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0just post in the channel, so we can all see it and thus help :)

AonZ
 3 years ago
Best ResponseYou've already chosen the best response.0got a link :P http://openstudy.com/study#/updates/519ff981e4b04449b221f091 but Question is Eliminate A from each pair of parametric equations x = 2tan( A/2) y = cosA

dan815
 3 years ago
Best ResponseYou've already chosen the best response.02 ways to go from cosa to a/2 or other way, which trig u know

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0theres also an identity u can use straight from tan to a double angle

dan815
 3 years ago
Best ResponseYou've already chosen the best response.0look at the formula for Cos(2a) and that tan^2a either one of those will help you simplify and eliminate a
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