Answer:
5km
Explanation:
A - her office
E - her home
AB = 1km; BC = CE = 4km
AE - the shortest disctance between her office and home.
ADE - right triangle, where AD = 4km, ED = 3 (EC - CD) =>
According to the Pythagorean theorem , we make up the equation:
AE = √ED^2 + AD^2 = √25 = 5km