cot(21^@40'+8^@20')=? 

দেওয়া আছে, \(cot(21^\circ 40' + 8^\circ 20')\)

আমরা জানি, 1° = 60'

তাহলে, \(21^\circ 40' + 8^\circ 20' = (21+8)^\circ + (40+20)'\)

\(= 29^\circ + 60'\)

\(= 29^\circ + 1^\circ\) [যেহেতু 60' = 1°]

\(= 30^\circ\)

সুতরাং, \(cot(21^\circ 40' + 8^\circ 20') = cot(30^\circ)\)

আমরা জানি, \(cot(30^\circ) = \sqrt{3}\)

অতএব, \(cot(21^\circ 40' + 8^\circ 20') = \sqrt{3}\) 🥳