Answer:
27mi
Step-by-step explanation:
Since the sailing course is equilateral in shape, then all their sides are equal.
Get one of the sides using Pythagoras theorem as shown;
Let one of the side be x
Two base will be x/2
According to the theorem;
x² = 9² +(x/2)²
x² = 81 + x²/4
x²-x²/4 = 81
3x²/4 = 81
3x² = 324
x² = 324/4
x² = 81
x = 9
Perimeter of the triangle = 3x
Perimeter of the triangle = 3(9)
Perimeter of the triangle = 27mi
