Q42 / 105 · NTA Abhyas (JEE Main) 2020 · Mathematics · Circle
If the length of direct common tangent and transverse common tangent of two circles with integral radii are units and unit respectively, then the reciprocal of the square of the distance between the centres of the circles is equal to
Correct answer: 0.1
Solution
Let two circles are of radii & and with centres & respectively, then
&
Assume, &
Then,
&
Assume, &
Then,
Hence, the correct answer is 0.1.