The cos and sin can be used for direction. all though change x is so much easier, but did you know change x is frame by frame and if you want it smooth use the sin and cos. you might not see its choppy, but it really is! you can compare it! try it. go remix the project and test it A lot people don't use the cos or sin or all the other things like asin acon or atan or tan! i hope this was helpful for all scratchers old and new your pal -@Fwlop
