Just a little trig help

59
0
1. The problem statement, all variables and given/known data

Well I'm following an example problem on this site:
http://www.batesville.k12.in.us/physics/PhyNet/Mechanics/Circular Motion/banked_with_friction.htm
I just need some help on the derivation math. I'll just host the image below.

2. Relevant equations
This is the problem equation:
http://img105.imageshack.us/img105/3449/frictioneqn4.th.gif [Broken]

On the last line when it goes from sines and cosines to tangants I can't follow what the person did.


3. The attempt at a solution

I'm assuming he used some type of trig Identity but I can't find one that is apt. I thinking it's a sum/difference trig identity but it just doesn't help. What could he be doing?

Any help at all is GREATLY apperciated!

Thanks
 
Last edited by a moderator:

LowlyPion

Homework Helper
3,055
4
Multiply top and bottom by 1/cosθ
 

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