wheel of 20cm radius.

circumference = 2pi(r) = 2pi(20) cm.

It rolls 60 cm, so,

60/[2pi(20)] = 3/(2pi) revolutions.

one revolution is 2pi, so,

[3/(2pi) rev]*[2pi / rev]

= 3

= 3 radians the wheel has turned. -----------answer.

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Another way.

One turn = 2pi radians ===>one circumference = 2pi(20) = 40pi cm.

Let x = radians turned in traveling 60 cm.

So, by proportion,

2pi/(40pi) = x/60

Cross multiply,

2pi(60) = (40pi)x

120pi = 40pi(x)

x = 120pi/(40pi) = 3 radians -----------answer.