$\"\"$

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The equation for graph is either $\"\"$ or $\"\"$ , $\"\"$ .

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Observe the graph:

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Since the graph is symmetric with respect to the polar axis, the polar equation is a cosine function.

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The polar equation is $\"\"$ .

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Find the values of $\"\"$ and $\"\"$ .

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The points on the graph are $\"\"$ and $\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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Substitute $\"\"$ .

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$\"\"$

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$\"\"$ .

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Substitute $\"\"$ and $\"\"$ in $\"\"$ .

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$\"\"$ .

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The polar equation is $\"\"$ .

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$\"\"$

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The polar equation is $\"\"$ .