Mathematics

Problem

\triangle ABC

and

\triangle PQR

, the correspondence is

A\leftrightarrow P,\;B\leftrightarrow Q,\;C\leftrightarrow R

. The two triangles are congruent. If

BC = 7\,\text{cm}

AC = 9\,\text{cm}

and

PR = 9\,\text{cm}

, then the length of

QR

is a)

9\,\text{cm}

7\,\text{cm}

8\,\text{cm}

16\,\text{cm}