How to find the value of $cot -216^@$ ?

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Answer 1 · 2015-05-22T04:27:21

On the trig unit circle,

$cot (-216) = cot (360 - 216) = cot 144 = cot (180 - 36) = -cot 36$

Calculator gives tan (36) = 0.73 -> $cot (36)= 1/0.73 = 1.37$

$cot(-216) = -1.37$

How to find the value of cot -216^@cot -216^@?