Question

Can someone help me??

Answer 1

An arc is a portion of the circumference which is 2pr.  And you want the difference between the large and small arcs..

a=2pr(120/360)  (we are multiplying the circumference by a fraction of the angle vs a complete circle...)

And the difference we seek is between the large and small arcs so:

d=(2p/3)(R-r)

d=(2p/3)(5-4)

d=2p/3 cm

d≈2.1 cm  (to nearest tenth of a centimeter)