Calculating the value for cotangent.

• June 30th 2011, 06:16 AM
sterces
Calculating the value for cotangent.
My question says to "calculate the value for cotangent (0) if (0)=270 degrees, given in standard position"

Just calculating it and getting 1.8370 I got it counted wrong, and when I asked on another forum about it they had gone through and what seems like to me, they used quotient identities and put the cos(270)/(sin(270) to equal 0.

Is that the right way to go about this? It didn't say to use quotient identities so I wasn't sure.

There's a second question with the same degree but its asking for the csc (cosecant) of 270, given in standard position.
• June 30th 2011, 06:35 AM
Also sprach Zarathustra
Re: Calculating the value for cotangent.
Quote:

Originally Posted by sterces
My question says to "calculate the value for cotangent (0) if (0)=270 degrees, given in standard position"

Just calculating it and getting 1.8370 I got it counted wrong, and when I asked on another forum about it they had gone through and what seems like to me, they used quotient identities and put the cos(270)/(sin(270) to equal 0.

Is that the right way to go about this? It didn't say to use quotient identities so I wasn't sure.

There's a second question with the same degree but its asking for the csc (cosecant) of 270, given in standard position.

...some smart people you found out there...

It's true.
$\theta=270^{\circ}$
$\cot(\theta)=\frac{\cos(\theta)}{\sin(\theta)}=\fr ac{\cos(270^{\circ})}{\sin(270^{\circ})}=\frac{0}{-1}=0$

EDIT:
$\sec(\theta)=\frac{1}{\cos(\theta)}$

So, what is $\sec(270^{\circ})$ ?
• June 30th 2011, 06:42 AM
sterces
Re: Calculating the value for cotangent.
Ah, alright, thanks for verifying :)
sec(270) would be -1 then.
• June 30th 2011, 06:44 AM
Also sprach Zarathustra
Re: Calculating the value for cotangent.
Quote:

Originally Posted by sterces
Ah, alright, thanks for verifying :)
sec(270) would be -1 then.

Yes!(But only by my definition of sec function)(Crying)
• June 30th 2011, 07:27 AM
e^(i*pi)
Re: Calculating the value for cotangent.
Quote:

Originally Posted by Also sprach Zarathustra

$\sec(\theta)=\frac{1}{\sin(\theta)}$

$\sec(x) = \dfrac{1}{\cos(x)}$ rather than 1/sin(x).
• June 30th 2011, 07:37 AM
Also sprach Zarathustra
Re: Calculating the value for cotangent.
Quote:

Originally Posted by sterces
Ah, alright, thanks for verifying :)
sec(270) would be -1 then.

No!

sec(270)=1/cos(270)=1/0
• June 30th 2011, 11:56 AM
Opalg
Re: Calculating the value for cotangent.
Quote:

Originally Posted by Also sprach Zarathustra
No!

sec(270)=1/cos(270)=1/0

But the question doesn't ask for $\sec(270^\circ)$, it asks for $\csc(270^\circ) = \frac1{\sin(270^\circ)} = \frac1{-1} = -1$.