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If x = acosecθ + b cotθ, y = bcosecθ + a cot θ, then what will be the value of x2−y2\text{x}^2-\text{y}^2x2−y2​ ?
Question

If x = acosecθ + b cotθ, y = bcosecθ + a cot θ, then what will be the value of x2y2\text{x}^2-\text{y}^2​ ?

A.

a2b2\text{a}^2-\text{b}^2​​

B.

a2+b2\text{a}^2+\text{b}^2​​

C.

a + b

D.

0

Correct option is A

Given:

x=acosecθ+bcotθx = a \cosec\theta + b \cot\theta​​
y=bcosecθ+acotθy = b \cosec\theta + a \cot\theta​​

Formula Used:

cosec2θcot2θ=1\cosec^2\theta - \cot^2\theta = 1

x2 - y2 = (x - y) (x + y) 

Solution:

x+y=(a+b)cosecθ+(a+b)cotθ=(a+b)(cosecθ+cotθ)x + y = (a + b)\cosec\theta + (a + b)\cot\theta = (a + b)(\cosec\theta + \cot\theta) ​

xy=(ab)cosecθ+(ba)cotθ=(ab)(cosecθcotθ)x - y = (a - b)\cosec\theta + (b - a)\cot\theta = (a - b)(\cosec\theta - \cot\theta)

x2y2=(a+b)(cosecθ+cotθ)×(ab)(cosecθcotθ)x^2 - y^2 = (a + b)(\cosec\theta + \cot\theta) \times (a - b)(\cosec\theta - \cot\theta)

So,

x2y2=(a2b2)(cosec2θcot2θ)x^2 - y^2 = (a^2 - b^2)(\cosec^2\theta - \cot^2\theta)

x2y2=(a2b2)×1=a2b2x^2 - y^2 = (a^2 - b^2) \times 1 = a^2 - b^2

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