# Evaluate cot without using a calculator.

• Sep 30th 2012, 10:19 AM
RiderMind
Evaluate cot without using a calculator.
Hello. The questions I have is

Evaluate cot 45° without using a calculator by using ratios in a reference triangle.

I can figure out how to do it with cos, but not cot. I assume I'm missing something really simple on this. If you could please explain to me how I get this answer, I would really appreciate it. Thank you.
• Sep 30th 2012, 10:42 AM
Plato
Re: Evaluate cot without using a calculator.
Quote:

Originally Posted by RiderMind
Hello. The questions I have is
Evaluate cot 45° without using a calculator by using ratios in a reference triangle.

Hint $\displaystyle \sin(45^o)=\cos(45^o)~.$
• Sep 30th 2012, 10:59 AM
MarkFL
Re: Evaluate cot without using a calculator.
Hint: your reference triangle will be a right isosceles triangle.
• Sep 30th 2012, 11:45 AM
RiderMind
Re: Evaluate cot without using a calculator.
I'm sorry guys, I'm still completely lost.
• Sep 30th 2012, 12:00 PM
lebdim
Re: Evaluate cot without using a calculator.
cot 45° = cotangens 45° = cos(45°)/sin(45°) = ((sqrt(2)/2)/(sqrt(2)/2))=1
• Sep 30th 2012, 12:00 PM
Plato
Re: Evaluate cot without using a calculator.
Quote:

Originally Posted by RiderMind
I'm sorry guys, I'm still completely lost.

You had best learn some very basic trigonometry .

$\displaystyle cot(\theta)=\frac{\cos(\theta)}{\sin(\theta)}~.$