Math, asked by GeniusPratham, 1 year ago

1 + 1/cosA=tan^2a/secA-1
plz prove it class 11th

Answers

Answered by ASweety1431
5
1+1/cosA (given)

1+secA. {1/cosA=secA}

{(secA+1)(secA-1)}/(secA-1)

(sec^2A-1)/(secA-1)

tan^2A/secA-1. hence proved

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Answered by Anonymous
6
Correction :

Prove that ,

1 + ( 1 / cos A ) = tan²A / ( sec A - 1 )

Here is your answer :

L.H.S = 1 + ( 1 / cos A )

R.H.S = tan²A / ( sec A - 1 )

______________________
Using identity,

=> tan A = sin A / cos A

=> sec A = ( 1 / cos A )
_______________________

= ( sin²A / cos²A ) / [ ( 1 / cos a ) - 1

= ( sin²A / cos²A ) / [ ( 1 - cos A ) / cos A ]

= ( sin²A / cos²A ) × [ cos A / ( 1 - cos A ) ]

= ( sin²A / cos A ) × [ 1 / ( 1 - cos A ) ]

= ( sin²A ) / [ cos A ( 1 - cos A ) ]

= ( sin²A ) / [ cos A - cos²A ]

_______________________

Using formula,

=> sin²A = ( 1 - cos²A )
________________________

= ( 1 - cos²A ) / [ cos A ( 1 - cos A ) ]

= [ ( 1 )² - ( cos A )² ] / [ cos A ( 1 - cos A ) ]


Using identity,

=> ( a² - b² ) = ( a + b ) ( a - b )

= [ ( 1 + cos A ) ( 1 - cos A ) ] / [ cos A ( 1 - cos A ) ]

= ( 1 + cos A ) / cos A

= ( 1 / cos A ) + ( cos A / cos A )

= ( 1 / cos A ) + 1

=> 1 + ( 1 / cos A ) = L.H.S

Proved !!
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