Math, asked by BrainlyHelper, 11 months ago

Prove the following trigonometric identities. (\frac{1}{sec^{2}\Theta-cos^{2}\Theta}+\frac{1}{cosec^{2}\Theta-sin^{2}\Theta} )sin^{2}\Theta cos^{2}\Theta=\frac{1-sin^{2}\Theta cos^{2}\Theta}{2+sin^{2}\Theta cos^{2}\Theta}

Answers

Answered by nikitasingh79
24

Answer with Step-by-step explanation:

Given :  

(1/sec²θ − cos²θ + 1/cosec²θ − sin²θ) sin²θ cos²θ = 1− sin²θ cos²θ / (2 + sin²θcos²θ)

L.H.S :

(1/sec²θ − cos²θ + 1/cosec²θ − sin²θ) sin²θ cos²θ  

= [1/{(1/cos²θ) − cos²θ} + 1 / {(1/sin²θ) − sin²θ}] sin²θ cos²θ  

[By using, secθ = 1/ cosθ & cosecθ = 1/sinθ]

= [1/{(1 − cos⁴θ)/ cos²θ} + 1 /{(1− sin⁴θ)/sin²θ}] sin²θ cos²θ  

[By taking LCM]

= [(cos²θ/1 − cos⁴θ ) + (sin²θ / 1− sin⁴θ)] sin²θ cos²θ  

= [{(cos²θ/(1 + cos²θ)(1 − cos²θ)} + (sin²θ / (1+ sin²θ) (1 - sin²θ)} ] sin²θ cos²θ  

[By using identity , a² - b² = (a + b) (a - b) ]

= [{(cos²θ/(1 + cos²θ)(sin²θ)} + (sin²θ / (1+ sin²θ) (cos²θ)} ] sin²θ cos²θ  

[By using  an identity, (1- cos²θ) = sin²θ &  (1- sin²θ) = cos²θ]

=  [{(cos²θ × (1+ sin²θ) (cos²θ) + (sin²θ ×(1 + cos²θ)(sin²θ)} / sin²θ cos²θ (1 + cos²θ)(1 + sin²θ)]  × sin²θ cos²θ  

[By taking LCM]

= [{(cos⁴θ × (1 + sin²θ) + (sin⁴θ ×(1 + cos²θ)} /  (1 + cos²θ)(1 + sin²θ)]  

= [{(cos⁴θ + cos⁴θ sin²θ) + (sin⁴θ + sin⁴θ cos²θ)} /  (1 + cos²θ + sin²θ + sin²θ cos²θ)]

= [{(cos⁴θ + sin⁴θ +  cos²θ sin²θ(sin²θ + cos²θ)} /  (1 + 1 + sin²θ cos²θ)]

[By using the identity , sin² θ + cos² θ = 1 & taking cos²θ sin²θ  common]

= [{(cos⁴θ + sin⁴θ +  cos²θ sin²θ(1)} /  (2 + sin²θ cos²θ)]

[By using the identity , sin² θ + cos² θ = 1]

= [{(cos²θ)² + (sin²θ)² +  cos²θ sin²θ} / (2 + sin²θ cos²θ)]

= [{(cos²θ + sin²θ)² - 2 cos²θ sin²θ + cos²θ sin²θ } / (2 + sin²θ cos²θ)]

[By using identity , a² + b² = (a + b)² -  2ab ]

= [{(1)² -  cos²θ sin²θ } / (2 + sin²θ cos²θ)]

[By using the identity , sin² θ + cos² θ = 1]

= (1 -  sin²θ cos²θ) / (2 + sin²θ cos²θ)]

(1/sec²θ − cos²θ + 1/cosec²θ − sin²θ) sin²θ cos²θ = 1− sin²θ cos²θ / (2 + sin²θcos²θ)

L.H.S = R.H.S  

Hence Proved..

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Answered by SulagnaRoutray
36

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