title: Drawing a parabolic arc between two points based on a known projectile angle
body: <p>I am trying to draw an arc between two points that represents a projectile's path. The angle that the projectile leaves point A at is known, and the X/Y coordinates of both points are known.</p>
  
  <p><a href="https://i.stack.imgur.com/V5OfU.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/V5OfU.jpg" alt="enter image description here"></a></p>
  
  <p>I'm trying to figure out the math behind this, and how to draw it up in c#.</p>
  
  <p>Here is my failed attempt, based on some path examples I found</p>
  
  <pre><code>var g = new StreamGeometry();
  var xDistance = Math.Abs(pointA.X - pointB.X);
  var yDistance = Math.Abs(pointA.Y - pointB.Y);
  var angle = 60;
  var radiusX = xDistance / angle;
  var radiusY = yDistance / angle;
  
  using (var gc = g.Open())
  {
      gc.BeginFigure(
          startPoint: pointA,
          isFilled: false,
          isClosed: false);
  
      gc.ArcTo(
          point: pointB,
          size: new Size(radiusX, radiusY),
          rotationAngle: 0d,
          isLargeArc: false,
          sweepDirection: SweepDirection.Clockwise,
          isStroked: true,
          isSmoothJoin: false);
  }
  </code></pre>
  
  <p>Any help would be greatly appreciated!</p>
  
  <p>Edit #2 (added clarity): For this problem assume that physics play no role (no gravity, velocity, or any outside forces). The projectile is guaranteed to land at point B and move along a parabolic path. The vertex will be halfway between point A and point B on the horizontal axis. The angle that it launches at is the angle up from the ground (horizontal).</p>
  
  <p>So Point A (Ax, Ay) is known. 
  Point B (Bx, By) is known. 
  The angle of departure is known.
  The X half of the vertex is known (Vx = Abs(Ax - Bx)). </p>
  
  <p>Does this really boil down to needing to figure out the Y coordinate of the vertex? </p>