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 August 5th, 2012, 03:00 PM #1 Senior Member   Joined: Aug 2012 From: South Carolina Posts: 866 Thanks: 0 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.
 August 5th, 2012, 03:11 PM #2 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs 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.
 August 5th, 2012, 07:59 PM #3 Senior Member   Joined: Aug 2012 From: South Carolina Posts: 866 Thanks: 0 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
 August 5th, 2012, 08:05 PM #4 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs Re: Eliminate the parameter t. Find a rectangular equation f 1.) Squaring the equation for x we obtain: $x^2=t$ where $0\le x\le2$ Now, substitute for t into the equation for y: $y=2x^2+3$ 2.) Squaring both parametric equations, we get: $x^2=4^2\cos^2(t)$ $y^2=4^2\sin^2(t)$ Adding, we get: $x^2+y^2=4^2$$\sin^2(t)+\cos^2(t)$$$ Since by the Pythagorean identity $\sin^2$$\theta$$+\cos^2$$\theta$$=1$ we have: $x^2+y^2=4^2$
 August 5th, 2012, 08:43 PM #5 Senior Member   Joined: Aug 2012 From: South Carolina Posts: 866 Thanks: 0 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
 August 5th, 2012, 08:44 PM #6 Senior Member   Joined: Aug 2012 From: South Carolina Posts: 866 Thanks: 0 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
 August 5th, 2012, 08:56 PM #7 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs 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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