$\"\"$

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The equation is $\"\"$ .

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Let the functions are $\"\"$ and $\"\"$ .

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Draw a coordinate plane.

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Graph the function $\"\"$ .

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$\"\"$

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Graph the function $\"\"$ .

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$\"\"$

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Observe the above two graphs :

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The graphs of the two functions coincide.

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So, the equation appears to be an identity.

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$\"\"$

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Check algebraically :

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The identity is $\"\"$ .

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Consider left hand side identity : $\"\"$ .

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Multiply and divide the above expression by $\"\"$ .

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$\"\"$

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Pythagorean identity : $\"\"$ .

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$\"\"$

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= Right hand side identity.

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$\"\"$

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The equation $\"\"$ represents an identity.