cot=adjacent side to right angle/ opposite side to right angle=cos 50 degrees/sin 50 degrees=tan(pi/2-50 degrees)=1/tan 50 degrees
cot 50 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 50
Push "cot"
cot 50 degrees=tan((2 pi)/9)=0.84