# Trig-Type Help

**URL:** <https://forum.kirupa.com/t/trig-type-help/68988>\
**Category:** programming\
**Created:** [October 31, 2004, 1:56am UTC](https://forum.kirupa.com/t/trig-type-help/68988 "2004-10-31T01:56:07Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![dangerskew](https://avatars.discourse-cdn.com/v4/letter/d/a88e57/32.png) [@dangerskew](https://forum.kirupa.com/u/dangerskew)\
**Post date:** [October 31, 2004, 1:56am UTC](https://forum.kirupa.com/t/trig-type-help/68988/1 "2004-10-31T01:56:07Z")

</div>

I’m making a game (Viewable here: [http://www.geocities.com/djorkon/BattleProto.html](http://www.geocities.com/djorkon/BattleProto.html) ) and I need help. When you get in the one vehicle on the screen and go towards your enemies, how can I make it so that when a bullet hits the vehicle it deflects off in the same way a billiards ball in a frictionless invironment would deflect off a wall? I want to know how to do this with triginometry, because I’m not using xSpeed and ySpeed. I am currently just reversing the bullet’s rotation.