What is the value of $\frac{BC}{BD}$?

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Note: Figure not drawn to scale.
For triangle ABC, the length of

\overline{A B}

is 11 less than the length of

\overline{A C}

. Point D (not shown) lies on

\overline{A C}

such that

\overline{B D}

(not shown) is perpendicular to

\overline{A C}

What is the value of

\frac{B C}{B D}