Most of us learn trigonometry in high school. You may have solved problems like this then. Since then, you haven't had need to apply it, so you forgot it. This thread might show the practicality of trigonometry, but we have people here who put it in perspective. Basically, it occurred to [MENTION=163198]avhed[/MENTION] that a new headset may make a difference because he knew that head angles affect bike handling. [MENTION=158672]FBinNY[/MENTION] and others point out that it is a measurable difference but probably not a significant one. With the knowledge of how to use trig, we can predict when changes are likely and unlikely to be significant.

The point isn't that we all have to be wizards in all things we learn in school, but it is helpful to know what arts are out there and what they can achieve.