The trig would be
lerp(scrollx,player.x+sin(player.angle)*speed,2*dt)
And
lerp(scrolly,player.y+cos(player.angle)*speed,2*dt)
that didn't work either..thanks for trying..
I'm seeing your thinking though..
the way I think of how it is currently...
Way #1: the plain old lerp(scrollx,playerx) this is sort of like the player is dragging the camera around after him... so no matter what direction/position the camera is just trying get back to the center and the player is "out running the center" with speed (the speed is capped so the player doesn't ever get completely off screen).
Way #2: I need come up with a way for the player to instead "push" the camera, but it has to be a calculation that has speed as a factor, so that when the player stops, the player then catches up with the camera.
In the first instance we have scrollx and scrolly which is always the center of the screen. But in the 2nd case we don't have that constantly updated fixed point. It's like I need to create an invisible sprite that's in front of the player and it's distance is binded to the player's speed. but obviously there's a match solution. 
R0J0hound?