Answer:
40 m
Step-by-step explanation:
The perimeter of the flat, orange shape is the sum of all the sides that forms a boundary around the shape.
The shape is made up of 4 triangles having 2 equal side lengths each, which surrounds the center square.
Each side length of the triangle, that forms a boundary round the shape = 5 m.
There are 8 of this equal side length.
Perimeter = 8(5m) = 40 m
You need to find the circumference of the whole circular pool and then subtract from it the arc length that is 1/4 of the circumference. The circumference formula is C = (3.14)(d), which in our case is 3.14(40) which is 125.6. Now we need the arc length we need to take away. 1/4 of a circle corresponds to a 90 degree angle, so in the formula for arc length, we have this:

which equals 31.4. Now subtract that from the circumference of the whole circle and you get the outside of the circle minus that arc length. That's 94.2. But we have to go in the radius times 2 to enclose the pie shaped piece we cut away. So we have 134.2. She should've just stuck with enclosing the circle; she would have used less fencing!