If the perimeter of a semicircular protractor is 108 cm, then the diameter of the protractor is:
A
54 cm
B
42 cm
C
24 cm
D
108 cm
Correct Option:
B
Explanation
A semicircle's perimeter includes the semicircular arc plus the diameter, so P = πr + 2r. Taking π = 22/7, 108 = r(22/7 + 2) = r(36/7). Hence r = 21 cm and the diameter is 42 cm.
