Respuesta :

bhadelsimron19

Answer:

Step-by-step explanation:

pythagors theorem

a^2+b^2=c^2

15^2+x^2=21^2

225+x^2=441

x^2=441-225

x=[tex]\sqrt{216[/tex]

x=6[tex]\sqrt{6[/tex]

=14.69

x=14.7 km