How do you convert $r=8$ into rectangular equations?

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Answer 1 · 2016-08-12T13:57:28

$x^2+y^2 = 64$

With the pass equations

${(x = r cos theta), (y = r sin theta):}$

substituting we have

${(x = 8 cos theta), (y = 8 sin theta):}$

Squaring an adding we obtain the
circle's origin centered equation

$x^2+y^2 = 64$

How do you convert r=8r=8 into rectangular equations?