hello this maybe is wrong to ask but i wounder if any1 got a tips for a page that can help u if u got problem with geometry :/ maybe webblesion..?

well im reading a course named analysis and got problem with this geometry basicly i havent understand this (yet) well i can give u exemple what we doing.. Calculate https://webwork.math.su.se/webwork2_...3ffde44dc1.png. The answer may not contain trigonometric functions.

basicly we have been using calculater before but without calculate im really bad on this because i havent understand it (yet) so tips plz?