Draw a circle of radius 6 cm. From a point 10 cm away from its centre, construct the pair of tangents to the circle and measure their lengths.
Given that
Construct a circle of radius
, and
form its centre, construct the pair of tangents to the circle.
Find the length of tangents.
We follow the following steps to construct the given

tep of construction
Step: I- First of all we draw a circle of radius
.
Step: II- Make a point P at a distance of
, and join
.
Step: III -Draw a right bisector of
, intersecting
at Q .
Step: IV- Taking Q as centre and radius
, draw a circle to intersect the given circle at T and T’.
Step: V- Joins PT and PT’ to obtain the require tangents.
Thus,
are the required tangents.
Find the length of tangents.

As we know that $O T \perp P T$ and $\triangle O P T$ is right triangle.
Therefore,
$O T=6 \mathrm{~cm}$ and $P O=10 \mathrm{~cm}$
In $\triangle O P T$,
$P T^{2}=O P^{2}-O T^{2}$
$=10^{2}-6^{2}$
$=100-36$
$=64$
$P T=\sqrt{64}$
$=8$
Thus, the length of tangents $=8 \mathrm{~cm}$