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plot the position vector r(t)= (2cost)i+(3sint)j, such that 0< (or equal to) t<...

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binghams | Student, Undergraduate | (Level 1) Honors

Posted January 17, 2012 at 12:48 AM via web

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plot the position vector r(t)= (2cost)i+(3sint)j, such that 0< (or equal to) t< (or equal to) pi (360 degrees)

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sciencesolve | Teacher | (Level 3) Educator Emeritus

Posted January 17, 2012 at 2:17 AM (Answer #1)

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You need to plug some values of t in the equation of vector to get some position vectors.

I suggest you to select the following values for t: `t = 0, t = pi/2 ; t = pi ; t = 3pi/2.`

`` If t = 0 => x = 2cos 0 = 2; y = 3sin 0 = 0

If `t = pi/2 =gt x = 2cos (pi/2) = 0 ; y = 3 sin(pi/2) = 3`

If `t = pi =gt x = 2cos (pi) = -2; y = 3 sin(pi) = 0`

If `t = 3pi/2 =gt x = 2cos (3pi/2) =0; y = 3 sin(3pi/2) = -3`

Hence, sketching the graph of vector function yields an ellipse whose antipodal points are: (2,0);(-2,0);(0,3) and (0,-3), semi-minor axis b=2 and semi-major axis a=3.

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