Graph $r(t)$ for t = $\pi/4$: Position and Tangent Vectors

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SUMMARY

The discussion focuses on graphing the position vector and tangent vector for the parametric equation \( r(t) = \sin(t) \mathbf{i} + 2\cos(t) \mathbf{j} \) at \( t = \frac{\pi}{4} \). The position vector at this point is \( r\left(\frac{\pi}{4}\right) = \left\langle \frac{\sqrt{2}}{2}, \sqrt{2} \right\rangle \) and the tangent vector is \( r'\left(\frac{\pi}{4}\right) = \left\langle \frac{\sqrt{2}}{2}, -\sqrt{2} \right\rangle \). The original equation describes an ellipse, with the x-axis ranging from -1 to 1 and the y-axis from -2 to 2. Users sought assistance in graphing these vectors, highlighting the effectiveness of the Math Help Board (MHB) community.

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$r(t)=sin(t)$i $+ 2cos(t)$j
$t= \pi/4$

sketch the position vector and the tangent vector

$r'(t)=cos(t)$i $- 2sin(t)$j

$r(\pi/4)= \frac{\sqrt{2}}{2}$i $+ \sqrt{2}$j

$r'(\pi/4)= \frac{\sqrt{2}}{2}$i $- \sqrt{2}$j

$\left\langle \frac{\sqrt{2}}{2}, \sqrt{2} \right\rangle$
$\left\langle \frac{\sqrt{2}}{2}, - \sqrt{2} \right\rangle$

can someone help me graph these. the original equation is the graph of a ellipse/circle from -1 to 1 on the x-axis and -2 to 2 on the y axis
 
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ineedhelpnow said:
$r(t)=sin(t)$i $+ 2cos(t)$j
$t= \pi/4$

sketch the position vector and the tangent vector

$r'(t)=cos(t)$i $- 2sin(t)$j

$r(\pi/4)= \frac{\sqrt{2}}{2}$i $+ \sqrt{2}$j

$r'(\pi/4)= \frac{\sqrt{2}}{2}$i $- \sqrt{2}$j

$\left\langle \frac{\sqrt{2}}{2}, \sqrt{2} \right\rangle$
$\left\langle \frac{\sqrt{2}}{2}, - \sqrt{2} \right\rangle$

can someone help me graph these. the original equation is the graph of a ellipse/circle from -1 to 1 on the x-axis and -2 to 2 on the y axis

Let's see...

[desmos="-4,4,-3,3"]x^2+y^2/4=1;y=2x\left\{0<x<\frac{\sqrt{2}}{2}\right\};y=2\sqrt{2}-2x\left\{\frac{\sqrt{2}}{2}<x<\sqrt{2}\right\}[/desmos]
 
ok so i literally posted this question on a bunch of different sites and once again MHB was the first to succeed :) thanks ILS!
 

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