Mathematics
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OpenStudy (anonymous):
Graph each pair of parametric equations.
1.x = 3 sin3t
y = 3 cos3t
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ganeshie8 (ganeshie8):
square them and add
OpenStudy (anonymous):
x² = 9sin² 3t
y² = 9cos² 3t
OpenStudy (anonymous):
x² + y² = 9sin² 3t + 9cos² 3t = 9(sin² 3t + cos² 3t)
ganeshie8 (ganeshie8):
yess, next use the identity : \(\sin^2 \theta + \cos^2 \theta = 1\)
OpenStudy (anonymous):
sin² 3t + cos² 3t = 1, so...
x² + y² = 9
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ganeshie8 (ganeshie8):
yes, does that look familiar to u ?
OpenStudy (anonymous):
yess
ganeshie8 (ganeshie8):
draw it :)
OpenStudy (anonymous):
so now i graph
ganeshie8 (ganeshie8):
yes, just draw it, and after that u can figure out the direction
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OpenStudy (anonymous):
i think i need help is it graphed as a circle
ganeshie8 (ganeshie8):
you're right ! \(x^2+ y^2 = r^2\) is an equation of circle wid radius \(r\) and center at origin
ganeshie8 (ganeshie8):
|dw:1390132038158:dw|
OpenStudy (anonymous):
thank you!
ganeshie8 (ganeshie8):
wat about the direction ?
when u graph a parametric curve, u must specify direction also :)
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ganeshie8 (ganeshie8):
x = 3 sin3t
y = 3 cos3t
when t = 0, x = 0, y = 3
when t = pi/6, x = 3, y = 0
ganeshie8 (ganeshie8):
|dw:1390132355573:dw|