Answer:
16.9 m
Step-by-step explanation:
Start with a half a circle. The central angle of a semicircle is 180 deg.
Now subtract 21 deg on each side.
180 - 21 - 21 = 138
The central angle is 138 deg.
The radius is 7 m.
Now we use the formula for the length of an arc of a circle given the radius of the circle and the central angle of the arc.