Answer:
145.7 cm
Explanation:
You want the perimeter of a shape bounded by 4 semicircles of radius 10 cm and two straight lines 10 cm long.
Perimeter
The circumference of a circle with radius 10 cm is ...
C = 2πr
C = 2(3.142)(10 cm) = 62.84 cm
The shape is bounded (in part) by 4 semicircles, so 2 full circles. The length of the curved boundary is ...
curve length = 2 · (62.84 cm) = 125.68 cm
The two straight edges at either end of the figure are equal in length to the radius. That total length gets added to the curve length to form the perimeter.
P = straight length + curve length
P = 2·10 cm + 125.68 cm ≈ 145.7 cm
The perimeter is about 145.7 cm.