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want help in rewrite expression sqrt(81-x^(2))/x x=9 sin theta

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user354582 | (Level 1) Honors

Posted July 9, 2013 at 10:45 PM via web

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want help in rewrite expression

sqrt(81-x^(2))/x

x=9 sin theta

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llltkl | College Teacher | (Level 3) Valedictorian

Posted July 10, 2013 at 12:43 AM (Answer #1)

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Given `x=9sintheta`

To rewrite the expression `sqrt(81-x^(2))/x` plug in the value of x.

`sqrt((81-(9sintheta)^2)/(9sintheta))`

`=sqrt((81-81sin^2theta)/(9sintheta))`

`= sqrt((81(1-sin^2theta))/(9sintheta))`

`= sqrt((81*cos^2theta)/(9sintheta))`    `(sin^2theta=1-cos^2theta)`

`=3costheta/sqrtsintheta`

This is the required expression.

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