cheat sheets.

CONVERT RADIANS TO DEGREES AND DEGREES TO RADIANS
radians = degrees * Math.PI / 180
degrees = radians * 180 / Math.PI

ROTATE TO THE MOUSE (OR ANY POINT)
dx = mouseX - sprite.x;
dy = mouseY - sprite.y;
sprite.rotation = Math.atan2(dy, dx);

GET THE DISTANCE BETWEEN TWO POINTS
dx = x2 - x1;
dy = y2 - y1;
dist = Math.sqrt(dx*dx + dy*dy);

CONVERT ANGULAR VELOCITY TO X, Y VELOCITY
vx = speed * Math.cos(angle);
vy = speed * Math.sin(angle);