question_answer

A person starts from a point A and travels 3 km eastwards to B and then turns left and travels thrice that distance to reach C. He again turns left and travels five times the distance he covered between A and B and reaches his destination D. The shortest distance between the starting point and the destination is?

A) 12 km              

B) 15 km

C) 16 km              

D) 18 km

Correct Answer: B

Solution :

As wee know \[{{(ac)}^{2}}={{(ab)}^{2}}+{{(bc)}^{2}}\] \[{{(ac)}^{2}}={{(12)}^{2}}+{{(9)}^{2}}\] \[{{(ac)}^{2}}=144+81\] \[{{(ac)}^{2}}=225\] \[ac=\sqrt{225}=15\,\,km\]