1.

Cot theta. Tan(90-theta)-sec(90-theta) cosec theta +√3 tan 12.tan60.tan78=2

Answer»

let theta = A

According to the QUESTION,

COT A . TAN (90 - A) - SEC (90 - A) . cosecA + √3 . tan12 . TAN60 . tan78 =2

LHS : cot A . tan (90 - A) - sec (90 - A) . cosecA + √3 . tan12 . tan60 . tan78

  • cot A . cot A - cosec A . cosec A + √3 . tan (90 - 78) . 1/√3 . tan 78
  • cot²A - cosec²A + cot 78 . tan78
  • 1 + 1/tan 78 . tan78
  • 1 + 1 = 2 = RHS

Hence Proved !



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