Asinusoidal voltage is given by the expression =20cos(5π×103 +60°) v. determine its (a) frequency in hertz, (b) period in milliseconds, (c) amplitude in volts, and (d) phase angle in degrees

There are some placeholders in the expression, but they can be safely assumed

(a)

(b)

(c)

(d)

Explanation:

Sinusoidal Waves

An oscillating wave can be expressed as a sinusoidal function as follows

Where

The voltage of the question is the sinusoid expression  

(a) By comparing with the general formula we have

(b) The period is the reciprocal of the frequency:

Converting to milliseconds

(c) The amplitude is

(d) Phase angle:

i think its c if i'm wrong