1.

If (sin θ + cosec θ)2 + (cos θ + sec θ)2 = k + tan2 θ + cot2 θ, then the value of k is equal to:1. 52. 73. 24. 9

Answer» Correct Answer - Option 2 : 7

Given:

(sin θ + cosec θ)2 + (cos θ +  sec θ)2 = k + tanθ + cotθ 

Formula used:

(a + b)2 = a2 + 2ab + b2

sin2 θ + cos2 θ = 1

sec2 θ - tan2 θ = 1

cosec2 θ - cot2 θ = 1

sin θ × cosec θ = 1

cos θ × sec θ = 1

Calculation:

According to the question,

sin2 θ + cosec2 θ + 2 × sin θ × cosec θ + cos2 θ + sec2 θ + 2 × cos θ × sec θ = k + tan2 θ + cot2 θ 

⇒ 1 + cosec2 θ + 2 × 1 + sec2 θ + 2 × 1 = k + tan2 θ + cot2 θ 

⇒ 5 + (cosec2 θ - cot2 θ) + (sec2 θ - cot2 θ) = k

⇒ 5 + 1 + 1 = k

⇒ k = 7

∴ The value of k is 7.



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