Answer: 2.6
Explanation:
To find the length of the seam along the edges of the pillow, we calculate the perimeter of the outer semicircle and add the perimeter of the inner semicircle as well as the sides. Since the length of the sides of the pillow are 0.2 yards each, the diameter of the outer circle is 0.50+0.2+0.2=0.9 yards. So, the perimeter of the outer semicircle is,
POC=12πd=12π×0.9=0.45π yds
The perimeter of the inner semicircle is
PIC=12πd=12π×0.5=0.25π yds.
The total perimeter of the pillow is
PT=0.45π+0.25π+0.2+0.2=2.599 yds
Rounded to one decimal place, Alex will need 2.6 yds of thread.