Location based on rotation

Hey guys, math question here...


I'm trying to make it so when the player has his accelerate button down, the spaceship will emit fire particles.

The below code is what I use to generate the particles, x is the spaceships center x point, and the y is the spaceships center y point. (The image was mid handled)

		If burning
			EmitParticle(x,y,firepart,10)
		End If

As expected, it generates a stream of fire particles from the center point of the ship. And the ship rotates (it's an astroid clone)

So the problem is:

I want the particles to be on the back of the image( where the engine is ) and to do this would mean some trig math that I'm trying to figure out.

Any help appriciated!

PS. here is the player's ship image(20x20):



The vertice of the concave section of that polygon is where I need the particles to come from

particleX = Cos(rotationAngle-90) * -5 + shipX
particleY = Sin(rotationAngle-90) * -5 + shipY

You need the -90 because 0 degrees would usually be to the right, rather than straight up.

The -5 is my estimate of the distance from the centre to the 'particle emitter' of the ship. So you might need to tweak that value slightly.

Thanks GFK, just what I was looking for.