cosec 20° - sec 20° का मान किसके बराबर है?

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NDA (Held On: 10 Sept 2017) Maths Previous Year paper
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  1. 4
  2. 2
  3. 1
  4. -4

Answer (Detailed Solution Below)

Option 1 : 4
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NDA 01/2025: English Subject Test
30 Qs. 120 Marks 30 Mins

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संकल्पना:

त्रिकोणमितीय सर्वसमिका:

  • (cos A× cos B) – (sin A × sin B) = cos(A + B)
  • 2 × sin A × cos A = sin (2A)
  • sin (90 - θ) = cos θ

 

गणना:

दिया गया है कि: √3 cosec 20° – sec 20°

चूँकि हम जानते हैं कि, cosec θ = 1/ sin θ और sec θ = 1/ cos θ

चूँकि हम जानते हैं कि, cos 30° = √3 / 2, sin 30° = ½

चूँकि हम जानते हैं कि, (cos A × cos B) – (sin A × sin B) = cos(A + B)

चूँकि हम जानते हैं कि, 2 × sin A × cos A = sin (2A)

चूँकि हम जानते हैं कि, sin (90 - θ) = cos θ

⇒ 4

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