Points P (x_{1}, y_{1}) and Q(x_{2}, y_{2})

**(i)** When PQ is parallel to y axis then x_{1} = x_{2}

So, the distance between P and Q is given by

\( \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)

= \(\sqrt{ (y_2-y_1)^2}\)

= |y_{2} – y_{1}|

**(ii)** When PQ is parallel to the x-axis then y_{1} = y_{2}

So, the distance between P and Q is given by =

\( \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)

= \(\sqrt{ (x_2-x_1)^2}\)

= |x_{2} – x_{1}|

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