Pre-Calculus, 9th edition
91

 PAGE: 407 SET: Exercises PROBLEM: 91

(a).

Show that .

The voltage is .

Where, the frequency is .

The power is

Where is resistance and is the time in seconds.

Substitute in .

Therefore, .

(b)

Observe the graph :

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

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

The geneal form of cosine function is .

Where, is amplitude and and is the phase shift.

Compare the equation with graph of the function.

Amplitude is and Period is .

.

Substitute all the values.

.

(c)

Deduce that .

Equate the two power functions.

Cancel the common terms.

.

(a) .

(b) .

(c) .

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