Answer:
46
Step-by-step explanation:
The following discussion assumes that this figure is 2-dimensional, and that "boundary" here means "perimeter."
Assume that the left and right boundaries of the figure are half circles. Then the "boundary" is the perimeter, that is, the distance completely around a circle of diameter 7; this is the circumference of the circle, and is 7π. Next, multiply the shown 12 by 2, obtaining 24.
Then the perimeter / boundary of the figure is 7π + 24, or about 46.
