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Ex 8.4, 5 (ix) - Chapter 8 Class 10 Introduction to Trignometry (Term 1)

Last updated at March 16, 2023 by

Ex 8.4, 5 - Chapter 8 Class 10 Introduction to Trignometry - Part 18

Ex 8.4, 5 - Chapter 8 Class 10 Introduction to Trignometry - Part 19

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Ex 8.4, 5 Prove the following identities, where the angles involved are acute angles for which the expressions are defined. (ix) (cosec A sin A)(sec A cos A) = 1/( +cot ) [Hint : Simplify LHS and RHS separately] Taking L.H.S (cosec A sin A) (sec A cos A) = (1/sin sin )(1/cos cos ) = ((1 2 ))/sin ((1 2 ))/cos = 2 /sin ( 2 )/cos = sin A cos A Taking R.H.S 1/( +cot ) = 1/(sin /cos + cos /sin ) = 1/(sin (sin ) + cos (cos ) /cos sin ) = 1/(( 2 + 2 )/cos sin ) = sin . cos /( 2 + 2 ) = sin . cos /1 = sin A cos A = L.H.S Hence proved

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