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Mathematics

Evaluate :

cosec2 57° - tan2 33° + cos 44° cosec 46° - 2\sqrt{2} cos 45° - tan2 60°

Trigonometric Identities

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Answer

Solving,

⇒ cosec2 57° - tan2 33° + cos 44° cosec 46° - 2\sqrt{2} cos 45° - tan2 60°

⇒ cosec2 57° - tan2 (90° - 57°) + cos 44° cosec (90° - 44°) - 2×12(3)2\sqrt{2} \times \dfrac{1}{\sqrt{2}} - (\sqrt{3})^2

By formula,

tan(90° - A) = cot A and cosec(90° - A) = sec A

⇒ cosec2 57° - cot2 57° + cos 44° sec 44° - 1 - 3

By formula,

cosec2 A - cot2 A = 1

⇒ 1 + cos 44° ×1cos 44°\times \dfrac{1}{\text{cos 44°}} - 1 - 3

⇒ 1 + 1 - 1 - 3

⇒ -2.

Hence, cosec2 57° - tan2 33° + cos 44° cosec 46° - 2\sqrt{2} cos 45° - tan2 60° = -2.

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