Multiple choice

Radii of two circles are 12 cm and 5 cm. Distance between their centres is 25 cm. What is the length of the direct common tangent?

  1. 21 cm

  2. 24 cm

  3. 22 cm

  4. 23 cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Length of direct common tangent = sqrt(d^2 - (R - r)^2), where d = 25, R = 12, r = 5. Length = sqrt(25^2 - (12 - 5)^2) = sqrt(625 - 49) = sqrt(576) = 24 cm.

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