More projectile math questions

cur_speed_x=cur_speedMath.cos(angleMath.PI/180);
cur_speed_y=cur_speedMath.sin(angleMath.PI/180);

and in a loop for motion:

bullet1.x = bullet1.x + (cur_speed_x / 10);
bullet1.y = bullet1.y - (cur_speed_y / 10);
cur_speed_y = cur_speed_y - g / 50;

the projectile is an a missile so i want to rotate the missile along the tangent of the path so it looks like it’s flying through the air. anyone know the formula to calculate this?

also down the line i’d like to make it so if you press a key you get a burst of thrust on the missile. any idea of how to add that?