$( A) \ 3\ cm$
$( B) \ 4\ cm$
$( C) \ 5\ cm$
$( D) \ 6\ cm$"
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In fig., PA and PB are two tangents drawn from an external point P to a circle and radius 4 cm. if PA$\perp $PB, then the length of each tangent is:

$( A) \ 3\ cm$
$( B) \ 4\ cm$
$( C) \ 5\ cm$
$( D) \ 6\ cm$"


Given: A circle with radius 4 cm, and two tangents PA and PB drawn to the circle from an external point P. And $PA\bot PB$

To do: To find the length of the tangents PA and PB. 

Solution: 

As given,
PA and PB are tangents to the circle at the points A and B respectively, from the exterrnal point P.

$\therefore PA=PB$, $( tangents\ drawn\ to\ a\ circle\ from\ an\ external\ point\ have\ equal\ length.)$

$\therefore CA\perp PA\ and\ CB\perp PB$

$\because$  Radius is always perpendicular to the tangent at the point of contact.

and $PA\bot PB$ $( given\ in\ the\ question)$

$CA=CB=$Radius of the circle

$\therefore$ APBC is a square having equal side 4 cm.

The length of eachh tangent is 4cm.

Therefore option $( B)$ is correct.

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Updated on: 10-Oct-2022

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