Two circles of diameters 4 cm and 16 cm are such that the distance between their centres is 10 cm. What is the length of a common tangent to the circles that does not intersect the line joining the centres?
Answer & explanation
Correct answer: option 2
Length of direct common tangent
= \(\sqrt {d^2-(r_1-r_2)^2}\)
= \(\sqrt {10^2-(2-8)^2}\)
= \(\sqrt {100-36}\) = 8 cm