cot 36 degrees=

cot=adjacent side to right angle/ opposite side to right angle=cos 36 degrees/sin 36 degrees=tan(pi/2-36 degrees)=1/tan 36 degrees

cot 36 degrees=

Using a calculator-make sure it is set to deg. Look at the top of the screen and it should say DEG and not RAD

input 36

Push "cot"

cot 36 degrees=sqrt(1+2/sqrt(5))=1.38

The other option is to use a standard trig chart

http://math2.org/math/trig/tables.htm

Find the cot for 36 degrees