How do you write the polar equation #r=3costheta# in rectangular form?

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Answer 1 · 2018-06-01T08:02:21

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#r = 3 cos theta #

#=> r^2 = 3 r cos theta #

Use your conversions:

#r^2 = x^2 + y^2 #

# r cos theta = x #

#r sin theta = y #

#color(red)(=> x^2+ y^2 = 3x #

You can also put this into the regular circle form

#=> x^2 - 3x + 9/4 + y^2 = 9/4 #

#color(red)(=> (x - 3/2 )^2 + y^2 = 9/4 #