Does the Nyquist Sampling theorem hold for a triangular wave produced by a function generator?
For example, a triangular wave with a frequency of 15 Hz sampled at 60 Hz, 180 Hz and 15000 Hz.
The Nyquist sampling theorem holds for bandlimited signals. Note that a perfect triangle wave is composed of a (convergent) infinite series of harmonics, which requires infinite bandwidth and is thus not bandlimited.
However, the energy remainder after a suffinciently large number of harmonics might be small enough than for a given noise floor that you can treat the portion of the triangle wave that is above that noise floor as bandlimited below some point above that last kept harmonic.