From: Richello on
Dear Sir,

Could you please help me to solve this or give me hints to do so?

An analogue signal x(t)=10cos(500πt) is sampled at 0, T,2T, .... with

I want to find a cosine y(t), whose frequency is as close as possible to
that of x(t), which when sampled with T=1ms yields the same sample values
as x(t). how can I get the equation of y(t)? .. then if x(nT) were the
input to a D/A converter, followed by a low-pass smoothing filter, why
would the output be x(t) and not y(t) ?