(b) Let the radius of circular garden be r.
Then, distance covered by crossing the garden diagonally = r + r = 2r
Also, distance covered when man follows the circular path =
(∵ man has to cover half of the circumference of circle)
= πr
Speed of man in m/s =
= m/s
Then By condition given in question,
− = 45
= 45;
(2Ï€ - 4)r = 135
r =
= =
= 59.21m
Then, circumference of grass plot = 2 π r
= 2 x 3.14 x 59.21 = 371.25 m