Step-by-step explanation:
Perimeter of semicircle =
Half of circumference of circle + diameter of circle =
[tex]\pi \: r + 2r \\ \\ = \frac{22}{7} \times 5.6 + 2 \times 5.6 \\ \\ = 22 \times 0.8 + 11.2 \\ \\ = 17.6 + 11.2 \\ \\ = 28.8 \: mm[/tex]
Thus, option B is the correct answer
