So we need to find the length of the hypotenuse of a right triangle with sides of 3 and 4, then add that distance to 3 and 4.
By the Pythagorean Theorme, the hypotenuse squared is equal to the sum of the sides squared...
d^2=3^2+4^2
d^2=9+16
d^2=25
d=√25
d=5
So the total distance of her run is 5+4+3=12 km
