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Consider the following : 1. tan^(2) t...

Consider the following :
1. `tan^(2) theta - sin^(2) theta = tan^(2) theta sin ^(2) theta `
2. `(1 + cot^(2) theta) (1 - cos theta) (1 + cos theta) = 1 `
Which of the statements given below is correct

A

1 only is the identiy

B

2 only is the identity

C

Both 1 and 2 are identity

D

Neither 1 nor 2 is the identity

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AI Generated Solution

The correct Answer is:
To determine the correctness of the given statements, we will analyze each statement step by step. ### Statement 1: **tan²θ - sin²θ = tan²θ * sin²θ** 1. **Start with the left-hand side (LHS)**: \[ \text{LHS} = \tan^2 \theta - \sin^2 \theta \] 2. **Substitute \(\tan^2 \theta\)**: \[ \tan^2 \theta = \frac{\sin^2 \theta}{\cos^2 \theta} \] So, \[ \text{LHS} = \frac{\sin^2 \theta}{\cos^2 \theta} - \sin^2 \theta \] 3. **Take LCM (Least Common Multiple)**: The LCM of \(\cos^2 \theta\) and 1 is \(\cos^2 \theta\): \[ \text{LHS} = \frac{\sin^2 \theta - \sin^2 \theta \cos^2 \theta}{\cos^2 \theta} \] 4. **Factor out \(\sin^2 \theta\)**: \[ \text{LHS} = \frac{\sin^2 \theta (1 - \cos^2 \theta)}{\cos^2 \theta} \] 5. **Use the Pythagorean identity**: \[ 1 - \cos^2 \theta = \sin^2 \theta \] Thus, \[ \text{LHS} = \frac{\sin^2 \theta \cdot \sin^2 \theta}{\cos^2 \theta} = \frac{\sin^4 \theta}{\cos^2 \theta} \] 6. **Now consider the right-hand side (RHS)**: \[ \text{RHS} = \tan^2 \theta \cdot \sin^2 \theta = \frac{\sin^2 \theta}{\cos^2 \theta} \cdot \sin^2 \theta = \frac{\sin^4 \theta}{\cos^2 \theta} \] 7. **Compare LHS and RHS**: \[ \text{LHS} = \text{RHS} \] Therefore, Statement 1 is **true**. ### Statement 2: **(1 + cot²θ)(1 - cosθ)(1 + cosθ) = 1** 1. **Start with the left-hand side (LHS)**: \[ \text{LHS} = (1 + \cot^2 \theta)(1 - \cos \theta)(1 + \cos \theta) \] 2. **Use the identity for cot²θ**: \[ 1 + \cot^2 \theta = \frac{1}{\sin^2 \theta} \] So, \[ \text{LHS} = \frac{1}{\sin^2 \theta} (1 - \cos \theta)(1 + \cos \theta) \] 3. **Simplify the product (1 - cosθ)(1 + cosθ)**: \[ (1 - \cos \theta)(1 + \cos \theta) = 1 - \cos^2 \theta = \sin^2 \theta \] 4. **Substituting back into LHS**: \[ \text{LHS} = \frac{1}{\sin^2 \theta} \cdot \sin^2 \theta = 1 \] 5. **Conclusion**: Therefore, Statement 2 is also **true**. ### Final Conclusion: Both statements are correct.
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S CHAND IIT JEE FOUNDATION-TRIGONOMETRICAL RATIOS -Question Bank - 32
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  7. If cos theta = (3)/(5) , then the value of (sin theta . tan theta + 1)...

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  8. If tan theta = (x)/(y) , " then " (x sin theta + y cos theta)/( x sin...

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  9. In a Delta ABC right angled at B, if tan A = (1)/( sqrt(3)) , find th...

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  10. If 7 sin A = 24 cos A then 14 tan A + 25 cos A - 7 sec A equals

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  11. The value of sin^2 theta cos^2 theta (sec^2 theta + cosec^2 theta ) is

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  12. Which of the following is not an identity ?

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  13. if x = a sec theta + b tan theta y = b sec theta + a tan theta ...

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  14. If x = a cos ^(3) theta and y = b sin ^(3) theta, then the value of ...

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  15. What is the value of (cosec A - sin A) (sec A - cos A) (tan A + cot A)...

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  16. What is the value of (sin^(3) x + cos^(3) x)/( sin x + cos x) + sin x...

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  17. (cos theta)/(1 - sin theta) + (cos theta)/( 1 + sin theta) equals

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  18. Consider the following : 1. tan^(2) theta - sin^(2) theta = tan^(2)...

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  19. sin^(4) theta + 2 cos^(2) theta (1 - (1)/( sec^(2) theta)) + cos ^(4) ...

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  20. If sin theta + sin ^(2) theta =1, " then" cos^(2) theta + cos^(4) the...

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