The perimeter of the green island is; 3.4 miles
We are given;
Perimeter of triangular Island = 6.8 miles
A channel divides the triangular island into 2 smaller islands.
Now, we are told that this channel is half the length of the distance between the lighthouses.
If the distance from one light house is x, the length of the channel is x/2.
Thus;
The channel cuts horizontally and green island is a small triangle while coconut island is a trapezium.
Since perimeter of the main triangular island is 6.8 miles, then;
3x = 6.8
x = 6.8/3
x = 2.267 miles
Then the perimeter of green island = (2.267/2) + (2.267/2) + (2.267/2) = 3.4 miles
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