Question

If the diameter of a circle is 5 centimeters, how long is the arc subtended by an angle measuring 60° ?

Answer 1

I think the answer will be 12 because 12 times 5 is 60°

Answer 2

arc length s is given by s = r*theta, where theta is the central angle in radians (not degrees).

Here the diam. is 5 cm, so the radius is 5/2 cm. 60 deg = sqrt(3) / 2. Thus,

the arc length is s = (5/2 cm)*sqrt(3) / 2. This simplifies to (5/4) sqrt(3).