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The equation in spherical coordinates is $\"\"$ .

To convert spherical coordinate system equation to rectangular coordinate system,

Substitute $\"\"$ , $\"\"$ and $\"\"$ .

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Take cosine of each side.

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Properties of inverse trigonometric function : $\"\"$ .

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Square on both sides.

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The equation in rectangular coordinates is $\"\"$ .

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The equation in rectangular coordinates is $\"\"$ .