This is a right triangle. To find the length of the hypotenuse a^2 + b^2 = c^2.
21^2 + 18^2 = c^2
441 + 324 = c^2
765 = c^2
27.66 km
Answer:

Step-by-step explanation:
The standard form of a quadratic is:

To complete the square, the a (leading coefficient) must be 1 and there can only be terms with variables on one side.
The expression given:

follows these rules. Next, we divide the b (linear coefficient) by 2, then square it. Basically:

The b in the expression is -18.


This is the number that is added.
N x 721 = 72.1
721n = 72.1 (put it in an easier format)
n = 0.1 (divide both sides by 721)
0.074 x n = 74
0.074n = 74 (put it in an easier format)
n = 1000 (divide both sides by 0.074)