Does trip trigger attack of opportunity when the PC has Improved Unarmed Strike?

Question

Trip

You can try to trip an opponent as an unarmed melee attack. You can only trip an opponent who is one size category larger than you, the same size, or smaller.

Making a Trip Attack

Make an unarmed melee touch attack against your target. This provokes an attack of opportunity from your target as normal for unarmed attacks.

So if a PC has Improved Unarmed Strike, which

Improved Unarmed Strike [General]

Benefit

You are considered to be armed even when unarmed —that is, you do not provoke attacks of opportunity from armed opponents when you attack them while unarmed. However, you still get an attack of opportunity against any opponent who makes an unarmed attack on you.

In addition, your unarmed strikes can deal lethal or nonlethal damage, at your option.

Normal

Without this feat, you are considered unarmed when attacking with an unarmed strike, and you can deal only nonlethal damage with such an attack.

Would they still be considered "unarmed" when making a trip without a trip weapon? I am confused as it says it would be a "unarmed melee touch attack".

Answer 1

Trip does not trigger an attack of opportunity when you have Improved Unarmed Strike

That is part of the benefit of Improved Unarmed Strike

you do not provoke attacks of opportunity from armed opponents when you attack them while unarmed

Making a trip attack only provokes an attack of opportunity from your target as normal for unarmed attacks, but you explicitly do not provoke attacks of opportunity as you normally would when you are unarmed. So you can trip them without provoking such an attack. You are still unarmed and still make unarmed attacks, but they do not count as unarmed for the purposes of provoking attacks of opportunity.

Answer 2

The key rules are included in your quotes:

Make an unarmed melee touch attack against your target.

And:

You are considered to be armed even when unarmed —that is, you do not provoke attacks of opportunity from armed opponents when you attack them while unarmed.

The "touch" part doesn't change the fact that you're making an "unarmed attack". Trip away!