Draw a circle of radius $3.5 \; cm$. Mark the center as $O$.
Mark a point $P$ outside the circle at a distance of $6 \; cm$ from the center.
Construct two tangents to the circle from the external point $P$.
Measure and write down the length of any one tangent.
Draw a circle with center $O$ and radius $3.5cm$
Mark point $P$ at a distance of $6 \; cm$ from the center $O$.
Join $PO$.
Draw the perpendicular bisector of $OP$.
Draw a circle with $OP$ as diameter which cuts the given circle at points $A$ and $B$.
Join $PA$ and $PB$.
$PA$ and $PB$ are the required tangents.
Length of tangent $PA = 5 \; cm$