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August 5th, 2012, 03:00 PM   #1
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Eliminate the parameter t. Find a rectangular equation for t

problem #1


x = sq.root of t, y = 2t + 3; 0 <= t <= 4



problem #2



x= 4 cos t, y = 4 sin t; 0 <= t <= 2pie


Thanks math community.
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August 5th, 2012, 03:11 PM   #2
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Re: Eliminate the parameter t. Find a rectangular equation f

1.) Take the equation for x and square it, then substitute for t into the equation for y and state the restricted domain.

2.) Square both equations, add together and factor the right side and use a Pythagorean identity on the trig. terms.

Let us know your results.
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August 5th, 2012, 07:59 PM   #3
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Re: Eliminate the parameter t. Find a rectangular equation f

stumped on the first problem

for #2 ... 16cost + 16sint

what next?

or do I go 4cost^2 + 4cost^2 = 1 so answer = 16 ???

Thanks Mark
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August 5th, 2012, 08:05 PM   #4
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Re: Eliminate the parameter t. Find a rectangular equation f

1.) Squaring the equation for x we obtain:

where

Now, substitute for t into the equation for y:



2.) Squaring both parametric equations, we get:





Adding, we get:



Since by the Pythagorean identity we have:

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August 5th, 2012, 08:43 PM   #5
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Re: Eliminate the parameter t. Find a rectangular equation f

ok now I follow u on both. that was too simple lol

I am done with trig after next week. I have IMO a horrible trig teacher Mark and I had long since shut down and tried to teach myself trig out of the book. this did not workout as I hoped, which in turn brought more frustration.

The instructor is great with math but has a very very heavy accent and his teaching style(again IMO) is very bad.

on the other hand I am doing great in Statistics and also have a great teacher in that class.

ok
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August 5th, 2012, 08:44 PM   #6
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Re: Eliminate the parameter t. Find a rectangular equation f

also Mark do I need to solve and/or factor more on these equations or is this final?

thanks
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August 5th, 2012, 08:56 PM   #7
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Re: Eliminate the parameter t. Find a rectangular equation f

Those answers are fine, I don't see how they can be further simplified, etc.

Sorry to hear your trig. teacher's style does not work for you.

Stats was my least favorite math class.
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