1.

If \(\tan 75^\circ = 2\; + \;\sqrt 3\), then the value of cot215° is –1). \(7\; + \;\sqrt 3 \)2). \(7 - 2\sqrt 3\)3). \(7\; + \;2\sqrt 3\)4). \(7\; + \;4\sqrt 3\)

Answer»

tan75° = 2 + √3

tan75° = cot15° = 2 + √3

cot215° = (2 + √3)2

cot215° = 4 + 3 + 4√3

cot215° = 7 + 4√3


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