So I'm looking at this example in my textbook where they're trying to find the vert. & horizontal tangent lines of r = sin Θ, 0 < Θ < pi. they say to first change it to parametric equations where(adsbygoogle = window.adsbygoogle || []).push({});

x = r cos Θ = sin Θ cos Θ

and

y = r sin Θ = sin Θ sin Θ = sin^2 Θ

But now I'm just really confused, how did they get these parametric equations?

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# Parametric Equations - Finding Tangent Lines

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