So if I have something like this..(adsbygoogle = window.adsbygoogle || []).push({});

[tex]rcos\theta =-r^{2}sin^{2}\theta[/tex]

I can cancel out one of the r to get

[tex]cos\theta = rsin^{2}\theta[/tex]

but how come when you have something like..

[tex]sin^2\theta = sin\theta[/tex]

and say you are trying to find the zeros of this equation, you can't just do

[tex]sin\theta = 1[/tex]

Is it because in the first example, we assume that r never = 0 so you can cancel it out where as in the [tex]sin\theta [/tex] example, it could be 0? Thanks.

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# Why are you allowed to do this?

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