Description: Sal finds a missing side length on a triangle when given its area. The triangle shown below has an area of 75 square units. Let me rotate this triangle, because then I think it might jump out at you how we can tackle this. So if I rotate, that is our rotated triangle and now it might be a little bit clearer what we're talking about, this length x that we want to figure out, this is our base.*Teacher Advisor is 100% free.