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NDA 2017 Maths · Mathematics · Straight Lines · easy

The distance of the point (2,1) from the line 5x-12y+7=0 is

Single correct option

The distance of the point (2,1)(2,1) from the line 5x−12y+7=05x-12y+7=0 is
  1. A. 517\frac{5}{17}
  2. B. 2913\frac{29}{13}
  3. C. 513\frac{5}{13}
  4. D. 713\frac{7}{13}
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Answer: (C) 513\frac{5}{13}

Distance =∣5(2)−12(1)+7∣52+122=513=\frac{|5(2)-12(1)+7|}{\sqrt{5^2+12^2}}=\frac{5}{13}. The value 517\frac{5}{17} comes from dividing by 5+125+12 instead of 25+144\sqrt{25+144}; 2913\frac{29}{13} comes from a sign slip that gives 10+12+710+12+7 in the numerator.
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Original question written in the NDA 2017 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake