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If sinθ + cosecθ = 2, then find the value of sin2θ + cos4θ - 2cosec2θ.1. -12. 13. -24. 2 |
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Answer» Correct Answer - Option 1 : -1 Given: sinθ + cosecθ = 2 Formula used: sin90° = 1 cos90° = 0 cosec90° = 1 sinθ = 1/cosecθ Calculation: sinθ + cosecθ = 2 ⇒ sinθ + (1/sinθ) = 2 But the above equation possible when sinθ = 1 ⇒ sinθ = sin90° After comparing we get θ = 90° sin2θ + cos4θ - 2cosec2θ ⇒ sin290° + cos490° - 2cosec290° ⇒ (1)2 + (0)4 - 2 × (1)2 ⇒ 1 + 0 - 2 ⇒ -1 ∴ The value is -1. |
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