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Prove that: cos-1 12/13 + sin-1 3/5 = sin-1 56/65 - Mathematics

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प्रश्न

Prove that:

`cos^(-1)  12/13 + sin^(-1)  3/5 = sin^(-1)  56/65`

प्रमेय
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उत्तर

Let x = `cos^(-1)  12/13` and y = `sin^(-1)  3/5`

or cos x = `12/13` and sin y = `3/5`

sin x = `sqrt (1 - cos^2 x)` and cos y = `sqrt(1 - sin^2 y)`

Now, sin x = `sqrt(1 - 144/169)` and cos y = `sqrt( 1 - 9/25)`

⇒ sin x = `5/13` and cos y = `4/5`

We know that,

sin (x + y) = sin x cos y + cos x sin y

= `5/13 xx 4/5 + 12/13 xx 3/5 `

= `20/65 + 36/65 `

= `56/65`

⇒ x + y = `sin ^-1(56/65)`

or, `cos^-1(12/13) + sin^-1 (3/5)`

= `sin^-1(56/65)`

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 2: Inverse Trigonometric Functions - Exercise 2.3 [पृष्ठ ५१]

APPEARS IN

एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 2 Inverse Trigonometric Functions
Exercise 2.3 | Q 6 | पृष्ठ ५१

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