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A pair of tangents are drawn from the or...

A pair of tangents are drawn from the origin to the circle `x^2+y^2+20(x+y)+20=0` . Then find its equations.

Text Solution

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The correct Answer is:
`2x^(2)+2y^(2)+5xy=0`

We have `S=x^(2)+y^(2)+20x+20y+20=0`
Equation of pair of tangents from origin is given by `T^(2) S S_(1)`.
or `(0.x+0.y+10(x+0)+10(y+0)+20)^(2)`
`=(x^(2)+y^(2)+20x+20y+20)(20)`
or `5(x+y+2)^(2)=(x^(2)+y^(2)+20x+20y+20)` or `2x^(2)+2y^(2)+5xy=0`
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