### trigonometry

#### How can I calculate the angle

I'm creating a game where if the enemy is in a certain range and is in front of the player the player can attack the enemy. I have worked out the radius distance and made it facing forward depending in which way the player faces but how can i create the angle so it makes like a cone shape from the player. I have got an image. The thin green line is the radius which I have worked out but how can i calculate the red cone. Here is the image for more better understanding http://tinypic.com/view.php?pic=28v63h0&s=6 This is what I done so far package { import flash.display.MovieClip; import flash.events.Event; import flash.events.KeyboardEvent; import flash.events.MouseEvent; import flash.ui.Keyboard; public class Player extends MovieClip { var radius:Number = 60; public function Player() { addEventListener(Event.ENTER_FRAME, Update); } function Update(event:Event) { var radiusx:Number = x+radius*Math.cos(rotation/180*Math.PI); var radiusy:Number = y+radius*Math.sin(rotation/180*Math.PI); // Rotate to mouse; var dx = parent.mouseX - x; var dy = parent.mouseY - y; var angle = Math.atan2(dy,dx) / Math.PI * 180; rotation = angle; } } }

You can use the definition of tangent: tan(a/2) = s/(2d) where s is size (diamerer) of the enemy and d is the shortest distance to the enemy. Here a is the total visible angle (between two red lines).

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