Draw A Triangle

var triangle:Shape; 

drawTriangle(0, 10, 100, 0xFF0000);

function drawTriangle(x:Number, y:Number, height:Number, color:uint){
  triangle = new Shape; 
  triangle.graphics.beginFill(color);
  triangle.graphics.moveTo(height/2, y);
  triangle.graphics.lineTo(height, height+y);
  triangle.graphics.lineTo(x, height+y);
  triangle.graphics.lineTo(height/2, y);
  addChild(triangle);  
}

Draw A Circle

var circle:Shape; 

drawCircle(100, 100, 75, 0xFF0000);

function drawCircle(x:Number, y:Number, radius:Number, color:uint){
 circle = new Shape; 
 circle.graphics.beginFill(color); 
 circle.graphics.drawCircle(x, y, radius);
 circle.graphics.endFill(); 
 addChild(circle);   
}

Draw A Rectangle

var rectangle:Shape; 

drawRectangle(0, 0, 200, 200, 0x0000FF); //Draws a rectangle at the origin

function drawRectangle(x:Number, y:Number, width:Number, height:Number, color:uint){
 rectangle = new Shape; 
 rectangle.graphics.beginFill(color); 
 rectangle.graphics.drawRect(x, y, width, height);
 rectangle.graphics.endFill(); 
 addChild(rectangle); 
}