I'm reading some EE material, and my trigonometry is really rusty.
There is an equation that looks like: $y(t) = \sin(2\pi \times 150 \times t)$
Why is there a $2\pi$ factor in the argument?
When I learned trig (many, many years ago), I learned equations that look like: $y(t) = \sin(150 t)$
where the $150$ was assumed to be in radians already.
Are these the same equation, and if so, when would I use one form but not the other?