diagonal = 9√2 ≈ 12.73
the diagonal splits the square into 2 right triangles with the hypotenuse being the diagonal of the square
using Pythagoras' identity
d = √(9² + 9²) = √162 = 9√2 ≈ 12.73 ( to 2 dec. places )
It’s C Beacuse I did it and it’s turn out as C
Answer:
It costs $154.88 to build the fences.
Step-by-step explanation:
Perimeter of square = 
We are given that A garden is in the shape of a square with a perimeter of 56 feet.
So,
Side =
So, Side of square park = 14 feet
One fence is around the perimeter of the garden, whereas the second fence is 2 feet from the first fence on the outside.
Outer length = 14+2+2=18 feet
So, Perimeter of outer fence = 
Cost of fencing 1 foot = $1.21
Cost of fencing 56 feet =
Cost of fencing 72 feet = 
Total cost = 67.76+87.12=154.88
Hence It costs $154.88 to build the fences.
Since the two labelled angles are corresponding angles, they are equal.
10x = 9x + 10
Subtract both sides by 9x
x = 10
Also, if you need to know, the angle length is 100 degrees.
Have an awesome day! :)