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In Fig. 2, O is the centre of the circle and LN is a diameter. If PQ is a tangent to the circle at K and \angle K\!LN=30^{\circ}, find \angle P\!K\!L.

 

 

 

 
 
 
 
 

Answers (1)

Given : \angle K\!LN=30^{\circ}

In \bigtriangleup LK\!N,

\angle LK\!N = 90^{\circ}  ( angle subtended by diameter on the circumference of the circle is 90^{\circ})

Also, OK= Radius of the circle.

\angle O\!K\!P=90^{\circ}\;\;\;\;\; -(1)  (tangent at any point on the circle is perpendicular to the radius through the point of contact)

In \bigtriangleup LO\!K,

\angle LO\!K=90^{\circ}

\angle K\!LN=30^{\circ}  (Given)

\angle LK\!O + \angle LO\!K + \angle K\!L\!N=180^{\circ}  (Sum of angles of a triangle)

\angle LK\!O + 90^{\circ} + 30^{\circ}=180^{\circ}

\angle LK\!O = 180^{\circ} + 120^{\circ}=60^{\circ}

\angle O\!K\!P = 90^{\circ}    - (from (1))

\angle O\!K\!P = \angle LK\!O + \angle P\!K\!L = 90^{\circ}

\Rightarrow 60^{\circ} + \angle P\!K\!L = 90^{\circ}

\Rightarrow \angle P\!K\!L = 90^{\circ} - 60^{\circ}

\Rightarrow \angle P\!K\!L = 30^{\circ}

 

Posted by

Safeer PP

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