# How do I have an arrow follow different height parabolas depending on how long the player holds down a key?

i'm trying to throw an arrow in my game, but i'm having a hard time trying to realize how to make a good parabola.

What I need: The more you hold "enter" stronger the arrow goes. The arrow angle will be always the same, 45 degrees.

This is what I have already have:

    private float velocityHeld = 1f;
protected override void Update(GameTime gameTime)
{
private void GetKeyboardEvent()
{
if (Keyboard.GetState().IsKeyDown(Keys.Enter) && !released)
{
timeHeld += velocityHeld;
holding = true;
}
else
{
if (holding)
{
released = true;
holding = false;
lastTimeHeld = timeHeld;
}
}
}

if (released && timeHeld > 0)
{
double vy = timeHeld * Math.Sin(alpha);
double vx = timeHeld * Math.Cos(alpha);

timeHeld -= velocityHeld;
}
else
{
released = false;

}
}


My question is, what do I need to do to make the arrow to go bottom as it loses velocity (timeHeld) to make a perfect parabola?