If two circles of radii 18 cm and 8 cm touch externally, then the length of a direct common tangent is :
Answer & explanation
Correct answer: option 1
Formula to be used
2\(\sqrt {R1\; × \; R2 }\)
Calculations
R1 = 18 cm.
R2 = 8 cm.
So, direct common tangent = 2\(\sqrt {18\; × \; 8 }\)
⇒ 2\(\sqrt {144}\)
⇒ 2 x 12
⇒ 24 cm
Therefore, the length of direct common tangent is 24 cm.