First the cow gets to meander about 1/4 of a full circle radius 120 ft 1/4 pi (1202)
when it gets up just right of 'a' the rope is now shorter by length 'b' so 60 ft
mooster gets 1/4 of a circle radius 60 ft 1/4 pi (602)
gets to the left of 'a' rope is shorter again by 'a' so 30 ft
area is 1/4 of a circle radius 30 1/4 pi 302
When it gets to intersection of d and e the rope gets 70 ft shorter so 50 ft long
1/4 of circle radius 50 ft 1/4 pi 502
TOTAL area is the sum of the REDS above......