Average power of sinusoidal signal

[ngibson]

Homework Statement

Question: Consider the sinusoidal signal:
A*cos(\omegat + \phi)

Determine the average power

Homework Equations

This is my first real attempt in signals and I am really confused with the question...
I guess my question would be am I suppose to take the P = lim as t-> \infty \frac{1}{t} \int A*cos(\omegat + \phi) ?

The Attempt at a Solution

I have no attempted solution yet. I am really just trying to see how to start this problem and then go from there!

Please help. Thanks

 

[Fightfish]

The average value of a function is \frac{1}{t}\int f(t) \Delta t. For sinusoidal functions, we typically average over a period.
Also, power is proportional to amplitude squared.

 

[Redbelly98]

More information is required here.

Is "the signal" a voltage or a current? How much resistance is the signal connected to?

 

[Mr.Green]

The average power of the signal x(t) is given by:

P = lim _{T ---> infinity} * (1/T) * [ integration of x²(t) over (0 to T) with respect to t]

please ditinguish between "T" and "t". "T" is the period of the signal and "t" is the time.

If you integrate [A cos (ωt + ф)]² over (0 to T) and take the limit as T approaches infinity you will have the answer. The result should be [A²/2]

Hint: T in the denominator will be simplified with the T in the numerator after the integration and you have no need to substitue any value instead of T.