Two circles of radii 20 cm and 5 cm, respectively, touch each other externally at the point P, AB is the direct common tangent of those two circles of centres R and S, respectively. The length of AB is equal to:
Answer & explanation
Correct answer: option 4
If,
r1 = Radius of 1st circle
r2 = Radius of 2nd circle
Then the direct common tangent = 2 \(\sqrt {r1r2}\)
= 2 \(\sqrt {20 × 5}\) = 20 cm