private float speedX = 5f;
private float speedY = 5f;
private int angle = 45;
 
// Randkollision           
if (Position.X <= 0) { speedX = speedX * -1; }
if (Position.X >= 600 - Texture.Width) { speedX = speedX * -1; }
if (Position.Y <= 0) { speedY = speedY * -1; }
if (Position.Y >= 800 - Texture.Height) { speedY = speedY * -1; }

position.X += speedX * (float)Math.Cos(MathHelper.ToRadians(angle));
position.Y += speedY * (float)Math.Sin(MathHelper.ToRadians(angle));