hey guys I am fiddling with learning by making asteroids type space game and such. It is 2d.

In this I have the 'view' fixed on the playership at the centre of the screen.

I want to calculate constantly the arc seen in the image below which is directly ahead of the ship. This would be a frontal firing arc. http://imageshack.us/photo/my-images/593/arcx.png/

This is where I am stumped. Having gone through so many maths lessons the past few days on py theorem etc...

Your ship rotates based on an angle based on your left/right input via kieyboard. So I know what direction the ship is facing in terms of a bearing. That value is held in the variable 'angle'.

Of course I know where my ship XY is, and I know where enemy ships XY are. I've used atan2 and I have calculated the bearing or angle of the enemy ship from my ship. But this won't help to create a fixed firing 'arc' in front of my player ship.

Basically I need a formula or calculation to calculate that tangent as seen in the picture, no matter what direction I am facing or where I am. So the value of that 'area' in front of the ship always remains constant which means it is my frontal firing arc. Let's say a value of about 60 degrees. So quite a narrow firing arc.

I know how to check if a potential target is within said firing arc before being allowed to fire, but determining that arc in front my ship is giving me measles.

Can anyone shed some light?

thanks