If `x=sum_(n=0)^oocos^(2n)theta,y=sum_(n=0)^oosin^(2n)varphi,z=sum_(n=0)^oocos^(2n)thetasin^(2n)varphi,w h e r e0

Explanation

Given,`x=1/(1−cos^2phi)`
`=1/(sin^2phi)`

`y=1/(1−sin^2phi )`
`=1/(cos^2phi)`

`z=1/(1−sin^2phicos^2phi)`

Consider,

`xyz=1/(sin^2phicos^2phi(1−sin^2phicos^2phi))--------(1)`

Also,`xy+z =1/(sin^2phicos^2phi)+1/(1−sin^2phicos^2phi)`

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