# Thread: trig vid and question

1. ## trig vid and question

Hi all this vid is great to explain the cosine rule, for me a lot easier to grap than explained in my course book.
The Cosine Rule - GCSE and AS Maths revision - YouTube
after watching this, can anyone explain why(in my course book) the perpendicular is dropped, it seems a pointless exercise.

Dave

2. ## Re: trig vid` and question

I don't understand what you mean by "dropping the perpendicular"...