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सिद्ध कीजिए। tanA(1+tan2A)2+cotA(1+cot2A)2=sinAcosA - Mathematics 2 - Geometry [गणित २ - ज्यामिति]

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Question

सिद्ध कीजिए। 

`tanA/(1 + tan^2A)^2 + cotA/(1 + cot^2A)^2 = sinA cosA`

Sum

Solution

बायाँ पक्ष = `tanA/(1 + tan^2A)^2 + cotA/(1 + cot^2A)^2`

= `tanA/(sec^2A)^2 + cotA/(cosec^2A)^2` ..........`[(∵ 1 + tan^2A = sec^2A),(∵ 1 + cot^2A = cosec^2A)]`

= `tanA/sec^4A + cotA/(cosec^4A)`

= `tanA xx cos^4A + cotA xx sin^4A` ....`(∵ 1/secA = cosA, 1/(cosecA) = sinA)`

= `sinA/cosA xx cos^4A + cosA/sinA xx sin^4A` ......`(∵ tanA = sinA/cosA, cotA = cosA/sinA)`

= `sinA*cos^3A + cosA*sin^3A`

= `sinA*cosA(cos^2A + sin^2A)`

= sinA*cosA   (1) .............(∵ sin2A + cos2A = 1)

= sinA * cosA = दायाँ पक्ष

∴ बायाँ पक्ष = दायाँ पक्ष

∴ `tanA/(1 + tan^2A)^2 + cotA/(1 + cot^2A)^2 = sinA * cosA`.

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त्रिकोणमितीय सर्वसमिकाएँ
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Chapter 6: त्रिकोणमिति - प्रश्नसंग्रह 6.1 [Page 132]

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Balbharati Geometry (Mathematics 2) [Hindi] 10 Standard SSC Maharashtra State Board
Chapter 6 त्रिकोणमिति
प्रश्नसंग्रह 6.1 | Q 6. (10) | Page 132
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