An ant is moving around a few food pieces of different shapes scattered on the floor. For which food piece would the ant have to take a longer round?

a) Radius=2.8/2=1.4 cm
Perimeter of figure (a)=length of diameter + Circumference of the semicircle=2R+πR=2.8+22/7×1.4=7.2 cm
b) Radius=2.8/2=1.4 cm
Perimeter of figure (b)=2 times length of 1.5 cm + 2 times radius + circumference of semicircle=1.5×2+2R+πR=3+2.8+22/7×1.4=5.8+22/7×1.4=10.2 cm
c) Radius=2.8/2=1.4 cm
Perimeter of figure (c)=Circumference of semicircle + 2 times length 2 cm=2×2+πR=4+22/7×1.4=8.4 cm
So, figure (b) has the largest perimeter.
Hence, for food piece (b), the ant would have to take a longer round.