Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Mensuration: 3D

Question:

Three circles of radius 6 cm are kept touching each other. The string is tightly tied around these three circles. What is the length of the string?

Options:

36 + 12p cm

36 + 18p cm

24 + 36p cm

36 +20p cm

Correct Answer:

36 + 12p cm

Explanation:

The length of the string not in contact with the circle = 2r + 2r + 2r = 6r = 6 × 6 = 36

Here,

The angles swiped by the string on one circle is 120.

Length of string touching circle = \(\frac{2πr }{3}\) + \(\frac{2πr }{3}\) + \(\frac{2πr }{3}\) =\(\frac{6πr }{3}\)

= 2πr = 2 × 6 × π = 12π

Total length = 36 + 12π