$\"\"$

The points are $\"\"$ .

The length of $\"\"$ is the distance between the points P and Q. \ \

The distance between two points $\"\"$ is $\"d$ .

$\"\"$ (Substitute $\"\"$ )

$\"\"$ (Subtract: $\"\"$ ) $\"\"$

$\"\"$ (Evaluate powers: $\"\"$ )

$\"\"$ (Add: $\"\"$ ) $\"\"$

The length of $\"\"$ is $\"\"$ units.