Answer: 2 kilometers.
Step-by-step explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the Pythagorean Theorem:
c^2 = a^2 + b^2
Where c is the hypotenuse of the triangle, the longest side (in this case the distance between the courthouse and the city pool) and a and b are the other sides.
Replacing with the values given:
4.4^2 = 3.9^2 + b^2
19.36 = 15.21+b^2
19.36-15.21 = b^2
4.15 = b^2
√4.15 = b
b=2 km
Feel free to ask for more if needed or if you did not understand something.