Respuesta :
Correction from my spelling,
If she walks from A to C to B*
If you have any question upon my solution, please ask !
Hope this helps you :)
If she walks from A to C to B*
If you have any question upon my solution, please ask !
Hope this helps you :)

Answer:
Step-by-step explanation:
In this problem, you need to apply the Pythagorean theorem because you know this is a right triangle. The path from B to C to A is a right angle.
[tex]AB^{2}=BC^{2}+AC^{2}[/tex]
The only unknown is going to be BC, you can arrange again this
[tex]BC^{2}=AC^{2} - AB^{2}[/tex]
and change the values
[tex]BC^{2} =(BC + 21feet)^{2} - (BC + 24feet) ^{2}[/tex]
[tex]BC^{2} =(BC^{2} +2*21feet*BC+21^{2}feet) +( BC^{2} +2*24feet*BC +24^{2}feet)[/tex]
[tex]BC^{2}=6BC+476-441\\BC^{2}=6BC+135\\BC^{2}-6BC-135=0[/tex]
and apply Bhaskara rule
[tex]BC=15[/tex]
Now you can come back and know all the lengths
[tex]AC=BC+21feet\\AC=36feet\\AB=BC+24feet\\AB=39feet[/tex]\\[tex]BC=15feet[/tex]