Question

5.
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? Remember,
circumference of a circle can be obtained by using the expression c=2pr, where r is the
radius of the circle.
(a), 2.8 cm
(b)
2.8 cm
1.5 cm
(c )2.8 cm
2.8 cm
2 cm
2 cm​

Answer 1

$\pink{(a) \: perimeter \: of \: figure = \frac{2\pi \: r}{2r} = r(\pi + 2) }$

$\pink{ \frac{2.8}{2}(\pi + 2) = 7.19cm }$

$\purple{(b) \: perimeter = 1.5 + 1.5 + 2.8 + \pi( \frac{2.8}{2} ) = 10.19}$

$\orange{(c) \: perimeter = \pi( \frac{2.8}{2}) + 2 + 2 = 8.39 }$

clearly, for food $\red{B}$ the ant has to go more.