i will mark brainiest(pls help me :c)

Answer: 13.74m
Step-by-step explanation:
Perimeter of shaded region:
Perimeter of shaded region=area of rectangle- area of semicircle
l×w‐(πr²) - -> diameter of circle‐6m; Radius‐3
=8×6‐(3.14×3×3)
=42— 28.26=13.74m