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WAEC Mathematics 2016 Paper

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Question : 18

Total: 49

A straight line passes through the point P(1,2) and Q

(5,8). Calculate the length PQ

$4\sqrt{11}$
$4\sqrt{10}$
$2\sqrt{17}$
$2\sqrt{13}$

Solution:

Concept:

Use the distance formula to find the length between two points on a plane.

Explanation:

For points

P(x_1, y_1)

and

Q(x_2, y_2)

, the distance

PQ

is:

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

Here,

P(1,2)

and

Q(5,8)

.

So,

x_1 = 1

,

y_1 = 2

,

x_2 = 5

,

y_2 = 8

.

Substitute the values:

PQ = \sqrt{(5 - 1)^2 + (8 - 2)^2}

= \sqrt{4^2 + 6^2}

= \sqrt{16 + 36}

= \sqrt{52}

= 2\sqrt{13}

Answer:

2\sqrt{13}

, which is option D.

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