The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y). (1) y = 4 (2) r = [3]/[3 - cos(theta)]
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Originally Posted by magentarita The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y). (1) y = 4 (2) r = [3]/[3 - cos(theta)] (1) is already expressed in rectangular coordinates. (2) $\displaystyle \Rightarrow 3r - r \cos \theta = 3$. Substitute $\displaystyle x = r \cos \theta$ and $\displaystyle r = \sqrt{x^2 + y^2}$.
Originally Posted by mr fantastic (1) is already expressed in rectangular coordinates. (2) $\displaystyle \Rightarrow 3r - r \cos \theta = 3$. Substitute $\displaystyle x = r \cos \theta$ and $\displaystyle r = \sqrt{x^2 + y^2}$. Sorry, the first question should be r = 4 not y = 4. Can you show me now?
The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y). The second question is a fraction. (2) r = [3] divided by [3 - cos(theta)]
Originally Posted by magentarita The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y). The second question is a fraction. (2) r = [3] divided by [3 - cos(theta)] I realise that. The symbol => means 'it follows that'. Do you see how what I posted follows from the second question.
Originally Posted by magentarita Sorry, the first question should be r = 4 not y = 4. Can you show me now? r = 4 => r^2 = 16. Make the obvious substitution.
Originally Posted by mr fantastic r = 4 => r^2 = 16. Make the obvious substitution. I don't see the obvious substitution. Please, explain.
You should recall that $\displaystyle r^2 = x^2 + y^2$ which should remind you of a circle
Originally Posted by o_O You should recall that $\displaystyle r^2 = x^2 + y^2$ which should remind you of a circle Our teacher did not teach this to the class.
This link should help you out: Polar Coordinates
Originally Posted by o_O This link should help you out: Polar Coordinates This is a great website. I've seen it before.
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