## Confused about a Fundamental Trig Identity

Trigonometric ratios and functions, the unit circle, inverse trig functions, identities, trig graphs, etc.

### Confused about a Fundamental Trig Identity

Hello everyone,

My trig book lists the reciprocal identity of cot x as cot x = cos x/sin x. But the professor gave us a formula sheet with it listed as cot x = 1/tan x. All the rest of the formulas in both the book and handout are the same, and they're both titled "Fundamental Reciprocal Identities" So which cotangent one is correct? I'm confused.

Any help is greatly appreciated!
agenta1013

Posts: 8
Joined: Thu Oct 17, 2013 2:20 pm

### Re: Confused about a Fundamental Trig Identity

theyre both right:
1/tanx=1/(sinx/cosx)=(1/1)/(sinx/cosx)=(1/1)(cosx/sinx)=cosx/sinx=cotx

little_dragon

Posts: 172
Joined: Mon Dec 08, 2008 5:18 pm

### Re: Confused about a Fundamental Trig Identity

Thank you! That makes total sense--I don't know why I didn't think of that when it's so obvious
agenta1013

Posts: 8
Joined: Thu Oct 17, 2013 2:20 pm