Math, asked by granger48, 11 months ago

. show that cos square theta minus sin square theta equal to 2 tan theta upon 1 minus tan squared theta is not an identity ​

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Answered by Anonymous
3

Step-by-step explanation:

cos²theta-sin² theta = cos(2theta)-----(1)

2tan(theta)/1-tan² theta = tan(2theta)-(2)

समीकरण (1) एवं (2) से -

cos(2theta)=tan(2theta)

जो कि नहीं होता है।

Answered by amitnrw
8

we can say that Cos²θ - Sin²θ   =  2Tanθ /(1  - Tan²θ) is not an identity

Step-by-step explanation:

Cos²θ - Sin²θ   =  2Tanθ /(1  - Tan²θ)

Lets put θ = 30°

Cos²30° = 3/2

Sin²30° = 1/2

Tan²30° = 1/3

Tan30° = 1/√3

Putting these value

LHS = 3/2 - 1/2  = 2/2  = 1

RHS  = 2(1/√3)/(1  - 1/3)  = (2/√3)(2/3)  = 3/√3 = √3

1 ≠ √3

hence LHS ≠ RHS

Take other case

Lets put θ = 60°

Cos²60° = 1/2

Sin²60° = 3/2

Tan²60° = 3

Tan60° = √3

LHS = 1/2 - 3/2  = -2/2  = -1

RHS  = 2(√3)/(1  - 3)  = (2√3)(-2)  = - √3

-1 ≠ -√3

hence LHS ≠ RHS

Hence we can say that Cos²θ - Sin²θ   =  2Tanθ /(1  - Tan²θ) is not an identity

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