A) $ 5cm $
B) $ 5.5cm $
C) $ 6cm $
D) $ 6.5cm $
Correct Answer: D
$ \therefore $ $ PL=LR=\frac{PR}{2} $ (i) In $ \Delta PQR, $ $ (PR^{2})={{(PQ)}^{2}}+{{(QR)}^{2}} $ [by Pythagoras theorem] $ ={{(5)}^{2}}+{{(12)}^{2}} $ $ =25+144=169={{(13)}^{2}} $
$ \Rightarrow $ $ PR^{2}={{(13)}^{2}} $
$ \Rightarrow $ $ PR=13 $
Now, by theorem, it L is the mid-point of the hypotenuse PR of a right angled $ \Delta PQR. $
Then, $ QL=\frac{1}{2}PR=\frac{1}{2}(13)=6.5cm $