Answer:
[tex]BC=3.1416\ mm[/tex]
Step-by-step explanation:
we know that
[tex]AD=AB+BC+CD[/tex] ---> by addition segment postulate
we have
[tex]AB=5.61\ mm\\CD=2.4684\ mm\\AD=11.22\ mm[/tex]
substitute the given values
[tex]11.22=5.61+BC+2.4684[/tex]
Rewrite as
[tex]11.2200=5.6100+BC+2.4684[/tex]
Solve for BC
[tex]11.2200=(5.6100+2.4684)+BC[/tex]
[tex]11.2200=8.0784+BC[/tex]
[tex]BC=11.2200-8.0784[/tex]
[tex]BC=3.1416\ mm[/tex]