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Question
Choose the correct alternative:
If the lines 3x − 4y + 4 = 0 and 6x − 8y − 7 = 0 are tangents to a circle, then find the radius of the circle
Options
`3/4`
`4/3`
`1/4`
`7/4`
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Solution
`3/4`
Explanation;
Tangents are parallel to each other.
∴ Perpendicular distance between tangents = diameter
∴ `|(4 - (-7/2))/sqrt(3^2 + (-4)^2)|` = 2r
∴ `(15/2)/5` = 2r
∴ r = `3/4`.
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