My apologies, I meant angle of the sprite and not the angle of motion.
Ah, yes, that makes sense. And lucid's graphic should make it more clear.
But here is a practical example:
Again, the sprite is moving with 50 pixel per second at an angle of 10?
Now the sprite rotates to 330?. The player hits the thrust button (max speed again 50 pps)[or a planet gets into the influence of another mass, something like that]. Now you need to aim for a final
x-component cos(330) * 50 -> ca 43,3
y-component sin(330) * 50 -> -25
So you need to interpolate (qarp should do) between
x 49.24 and 43,3
y 8.68 and -25
for whatever time feels right for your game.