Ran into this question few days back, using the "line" triggering on one of my old scopes, lets say the scope triggers on 60hz, but does anyone know where in the cycle it triggers, could be anywhere in the cycle. Thanks

 

That's not how triggers work. You set the voltage that the scope will trigger not the frequency.

 

does anyone know where in the cycle it triggers, could be anywhere in the cycle.

Not sure, but you can test it.
Connect a piece of bare wire to the scope input and adjust the input sensitivity so you see the 60Hz pickup, while using the "line" triggering.
Does the phase of the displayed signal change if you adjust the trigger level?

 

That's not how triggers work. You set the voltage that the scope will trigger not the frequency.

The "line" trigger setting triggers on the incoming AC power frequency.

 

Oh a line trigger, ok. Well it's in the middle of the slope.

 

Oh a line trigger, ok. Well it's in the middle of the slope.

But the trigger level control may still be active so the trigger point can be varied.