The power in the signal $$s\left( t \right) = 8\cos \left( {20\pi t – {\pi \over 2}} \right) + 4\,\sin \left( {15\pi t} \right)$$ is

The correct answer is $\boxed{\text{A) 40}}$.

The power in a signal is given by the formula:

$$P = \frac{1}{2} \int_{-\infty}^{\infty} |s(t)|^2 dt$$

In this case, the signal is given by:

$$s(t) = 8\cos \left( {20\pi t – {\pi \over 2}} \right) + 4\,\sin \left( {15\pi t} \right)$$

The square of the absolute value of this signal is given by:

$$|s(t)|^2 = 64 \cos^2 \left( {20\pi t – {\pi \over 2}} \right) + 16 \cos \left( {20\pi t – {\pi \over 2}} \right) \sin \left( {15\pi t} \right) + 16 \sin

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