मराठी

Prove the Following Trigonometric Identities. (1 + Cot A − Cosec A) (1 + Tan A + Sec A) = 2

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प्रश्न

Prove the following trigonometric identities.

(1 + cot A − cosec A) (1 + tan A + sec A) = 2

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उत्तर

We have to prove  (1 + cot A − cosec A) (1 + tan A + sec A) = 2

We know that, `sin^2 A + cos^2 A = 1`

So.

`(1 + cot A − cosec A) (1 + tan A + sec A) = (1 + cosA/sin A - 1/ sinA) (1 + sin A/cos A + 1/cos A)` 

`= ((sin A + cos A - 1)/sin A)((cos A + sin A + 1)/cos A)`

`= ((sin A + cos A -1)(sin A + cos A  + 1))/(sin A cos A)`

`= ({(sin A + cos A) - 1}{(sin A + cos A) + 1})/(sin A cos A)`

`= ((sin A + cos A)^2 -1)/(sin A cos A)`

`= (sin^2 A + 2 sin A cos A + cos^2 A - 1)/(sin A cos A)`

`= ((sin^2 A + cos^2 A) + 2 sin A cos A - 1)/(sin A cos A)`

`= (1 + 2 sin A cos A  -1)/(sin A cos A)`

`= (2 sin A cos A)/(sin A cos A)`

= 2

Hence proved.

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पाठ 11: Trigonometric Identities - Exercise 11.1 [पृष्ठ ४६]

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आर.डी. शर्मा Mathematics [English] Class 10
पाठ 11 Trigonometric Identities
Exercise 11.1 | Q 60 | पृष्ठ ४६

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