$\"\"$

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(a).

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Show that $\"\"$ .

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The voltage $\"\"$ is $\"\"$ .

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Where, the frequency is $\"\"$ .

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The power $\"\"$ is $\"\"$

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Where $\"\"$ is resistance and $\"\"$ is the time in seconds.

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

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$\"\"$

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$\"\"$

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Therefore, $\"\"$ .

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$\"\"$

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(b)

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Observe the graph :

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The graph of the function does not passing through the origin and shifted $\"\"$ units downward.

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hence,the graph of the function is a cosine function.

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The geneal form of cosine function is $\"\"$ .

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Where, $\"\"$ is amplitude and $\"\"$ and $\"\"$ is the phase shift.

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Compare the equation with graph of the function.

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Amplitude is $\"\"$ and Period is $\"\"$ .

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$\"\"$

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$\"\"$ .

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Substitute all the values.

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$\"\"$

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$\"\"$ .

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$\"\"$

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(c)

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Deduce that $\"\"$ .

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$\"\"$

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$\"\"$

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Equate the two power functions.

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$\"\"$

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Cancel the common terms.

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$\"\"$ .

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$\"\"$

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(a) $\"\"$ .

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(b) $\"\"$ .

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(c) $\"\"$ .