# Phase angle of sine wave (confusion)

Usually, phasors are represented by Acos(ωt + φ) where φ is the phase angle. Using this convention, we need to convert sin(ωt) into cos(ωt - 90) to get its phase angle like this thumbnail on a YouTube video.

But in EE, the AC sources are usually sinusoids and back when I first studied about phasors in physics, they were introduced as Asin(ωt + φ) with φ being the phase angle.

What is the correct way to represent sine waves (say 120sin(120πt)) in polar form?

• I don't see that there is a best way; either or one might be more applicable to a particular problem. Commented Jun 5, 2021 at 10:39
• So there is no particular "convention"? Commented Jun 5, 2021 at 10:43
• There might be for some applications but you mention no applications. Commented Jun 5, 2021 at 10:53
• Say V = 120sin(120πt) Volts then according to EE convention it should be 120, angle(-90 degrees) ? Commented Jun 5, 2021 at 10:55
• There is no one, common convention. So even in the above comment example, it is ambiguous. To avoid ambiguity, always specify the reference phasor at the beginning itself.
– AJN
Commented Jun 5, 2021 at 11:11