Draw a line segment `P Q` length `8. 4\ c mdot` Draw the perpendicular bisector of this line segment.

Explanation

Steps of Construction :
1. With P and Q as centers, draw arcs on both sides of PQ with equal radii. The radius should be more than half the length of PQ.

2. Let these arcs cut each other at points R and RS.

3. Join RS which cuts PQ at D. Then RS=PQ. Also `anglePOR=90^*.
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Hence, the line segment RS is the perpendicular bisector of PQ as it bisects PQ at P and is also perpendicular to PQ. On measuring the lengths of PR=4.2cm, QR=4.2 cm Since PR=QR, both are 4.2cm each.

`therefore` `PR=QR`.