## Elementary Geometry for College Students (7th Edition)

a) $AD=4\sqrt {3}$ b) $BD=4.5$
a) $\frac{AD}{BD}=\frac{DC}{AD}$ $\frac{AD}{6}=\frac{8}{AD}$ $AD^{2}=8\times6$ $AD^{2}=48$ $AD=\sqrt {48}$ $AD=4\sqrt {3}$ b) $\frac{AD}{BD}=\frac{DC}{AD}$ $\frac{6}{BD}=\frac{8}{6}$ $6\times6=8BD$ $36=8BD$ $BD=\frac{9}{2}=4.5$