Answer:
3.5
Step-by-step explanation:
Look at the picture.
If ABC is any triangle and AD bisects (cuts in half) the angle BAC, then
[tex]\dfrac{AB}{BD}=\dfrac{AC}{DC}[/tex]
In our triangle we have the proportion:
[tex]\dfrac{CB}{DB}=\dfrac{CA}{DA}[/tex]
We have
CB = 6
DB = 4.2
CA = 5
DA = x
Substitute:
[tex]\dfrac{6}{4.2}=\dfrac{5}{x}[/tex] cross multiply
[tex]6x=(4.2)(5)[/tex]
[tex]6x=21[/tex] divide both sides by 6
[tex]x=3.5[/tex]
