A) $ \frac{5}{17} $
B) $ \frac{3}{19} $
C) $ \frac{7}{10} $
D) $ \frac{7}{13} $
Correct Answer: D
$ \Rightarrow $ $ 2\sin \theta \cos \theta ={{( \frac{17}{13} )}^{2}}-1 $
$ \Rightarrow $ $ 2\sin \theta \cos \theta =( \frac{17}{13}-1 )( \frac{17}{13}+1 ) $ $ =( \frac{4}{13} )( \frac{30}{13} )=\frac{120}{169} $ Now, $ {{(\sin \theta -\cos \theta )}^{2}}={{(\sin \theta +\cos \theta )}^{2}}-4\sin \theta \cos \theta $ $ ={{( \frac{17}{13} )}^{2}}-2\times \frac{120}{169} $ $ =\frac{289-240}{169}=\frac{49}{169} $
$ \therefore $ $ \sin \theta -\cos \theta =\frac{7}{13} $