Question

A ship sails 30 nautical km due West and 16 nautical km due North. How far is it from its starting point ?

• A. 34 nautical km
• B. 20 nautical km
• C. 17 nautical km
• D. 13 nautical km

Answer 1

The correct option is A

34 nautical km

Let the ship start at O and sail due West to A and then due North to B.

Using Pythagoras Theorem we have,

$O{B}^2=O{A}^2+A{B}^2$

$O{B}^2={30}^2+{16}^2$

$O{B}^2=(2\times 15{)}^2+(2\times 8{)}^2$

$O{B}^2=2^2({15}^2+8^2)$

$O{B}^2=2^2\left({17}^2\right).....(8-15-17\text{Pythagoras Triplet})$

$\text{OB}=34\text{cm}$