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Consider the following statements:I. 1/(1 + cosθ) + 1/(1 - cosθ) = 2cosec2θII. (1 + tan2θ)/ cosec2θ = tan2θWhich of the following statements are correct.1. Only 12. Only 23. Both 1 and 24. Neither 1 nor 2 |
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Answer» Correct Answer - Option 3 : Both 1 and 2 Given: Two identities are given Formula Used: Basic concept of trigonometric ratio and identities We know that (a2 – b2) = (a + b)(a - b) sin2θ + cos2θ = 1 1 + tan2θ = sec2θ sinθ = 1/cosecθ Calculation: The given identity is 1/(1 + cosθ) + 1/(1 - cosθ) = 2cosec2θ L.H.S. Take LCM of denominators ⇒ 2/(1 + cosθ) × (1 - cosθ) ⇒ 2/(1 - cos2θ) ⇒ 2/sin2θ ⇒ 2 cosec2θ = R.H.S. So, statement 1 is correct Now, the given identity is (1 + tan2θ)/ cosec2θ = tan2θ L.H.S. ⇒ (1 + tan2θ)/cosec2θ ⇒ sec2θ/cosec2θ ⇒ sin2θ/cos2θ ⇒ tan2θ = R.H.S. So, statement 2 is correct Hence, option (3) is correct |
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