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# Prave That: Tan a ( 1 + Tan 2 a ) 2 + Cot a ( 1 + Cot 2 a ) 2 = Sin a Cos a - Geometry

ConceptApplication of Trigonometry

#### Question

Prove that:

$\frac{\tan A}{\left( 1 + \tan^2 A \right)^2} + \frac{\cot A}{\left( 1 + \cot^2 A \right)^2} = \sin A \cos A$

#### Solution

$\frac{\tan A}{\left( 1 + \tan^2 A \right)^2} + \frac{\cot A}{\left( 1 + \cot^2 A \right)^2}$

$= \frac{\tan A}{\left( \sec^2 A \right)^2} + \frac{\cot A}{\left( {cosec}^2 A \right)^2} \left( 1 + \tan^2 \theta = \sec^2 \theta\text{ and }1 + \cot^2 \theta = {cosec}^2 \theta \right)$

$= \frac{\sin A}{\cos A } \times \cos^4 A + \frac{\cos A}{\sin A} \times \sin^4 A \left( \cos\theta = \frac{1}{\sec\theta}\text{ and }\sin\theta = \frac{1}{cosec\theta} \right)$

$= \sin A \cos^3 A + \cos A \sin^3 A$

$= \sin A\cos A\left( \cos^2 A + \sin^2 A \right)$

$= \sin A\cos A \left( \cos^2 \theta + \sin^2 \theta = 1 \right)$

Is there an error in this question or solution?

#### APPEARS IN

Balbharati Solution for Balbharati Class 10 Mathematics 2 Geometry (2018 to Current)
Chapter 6: Trigonometry
Practice set 6.1 | Q: 6.1 | Page no. 131
Solution Prave That: Tan a ( 1 + Tan 2 a ) 2 + Cot a ( 1 + Cot 2 a ) 2 = Sin a Cos a Concept: Application of Trigonometry.
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