Bend a 36 cm long wire into a semicircle. What is the radius of the semicircle ?

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answer is A.

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Detailed Solution

Concept- This question reveals some facts about the semicircle. A semicircle is a semicircle. You might think that the circumference of a semicircle is half the circumference of a circle. But that is not true. The circumference of a semicircle is half the circumference of the original circle plus the diameter. Since the semicircle contains a straight line that is the diameter, you need to include the diameter when calculating the circumference. The length of the wire is in the shape of a semicircle.
Given, length of wire

The wire length covers both the diameter and circumference of the semicircle.

Length of the wire

Hence, option 1 is correct.

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